cURL 7.68.0

What's new in this version:

Changes:
- TLS: add BearSSL vtls implementation
- XFERINFOFUNCTION: support CURL_PROGRESSFUNC_CONTINUE
- curl: add --etag-compare and --etag-save
- curl: add --parallel-immediate
- multi: add curl_multi_wakeup()
- openssl: CURLSSLOPT_NO_PARTIALCHAIN can disable partial cert chains

Bugfixes:
- CVE-2019-15601: file: on Windows, refuse paths that start with \
- Azure Pipelines: add several builds
- CMake: add support for building with the NSS vtls backend
- CURL-DISABLE: initial docs for the CURL_DISABLE_* defines
- CURLOPT_HEADERFUNCTION.3: Document that size is always 1
- CURLOPT_QUOTE.3: fix typos
- CURLOPT_READFUNCTION.3: fix the example
- CURLOPT_URL.3: "curl supports SMB version 1 (only)"
- CURLOPT_VERBOSE.3: see also ERRORBUFFER
- HISTORY: added cmake, HTTP/3 and parallel downloads with curl
- HISTORY: the SMB(S) support landed in 2014
- INSTALL.md: provide Android build instructions
- KNOWN_BUGS: Connection information when using TCP Fast Open
- KNOWN_BUGS: LDAP on Windows doesn't work correctly
- KNOWN_BUGS: TLS session cache doesn't work with TFO
- OPENSOCKETFUNCTION.3: correct the purpose description
- TrackMemory tests: always remove CR before LF
- altsvc: bump to h3-24
- altsvc: make the save function ignore NULL filenames
- build: Disable Visual Studio warning "conditional expression is constant"
- build: fix for CURL_DISABLE_DOH
- checksrc.bat: Add a check for vquic and vssh directories
- checksrc: repair the copyrightyear check
- cirrus-ci: enable clang sanitizers on freebsd 13
- cirrus: Drop the FreeBSD 10.4 build
- config-win32: cpu-machine-OS for Windows on ARM
- configure: avoid unportable `==' test(1) operator
- configure: enable IPv6 support without `getaddrinfo`
- configure: fix typo in help text
- conncache: CONNECT_ONLY connections assumed always in-use
- conncache: fix multi-thread use of shared connection cache
- copyrights: fix copyright year range
- create_conn: prefer multiplexing to using new connections
- curl -w: handle a blank input file correctly
- curl.h: add two missing defines for "pre ISO C" compilers
- curl/parseconfig: fix mem-leak
- curl/parseconfig: use curl_free() to free memory allocated by libcurl
- curl: cleanup multi handle on failure
- curl: fix --upload-file . hangs if delay in STDIN
- curl: fix -T globbing
- curl: improved cleanup in upload error path
- curl: make a few char pointers point to const char instead
- curl: properly free mimepost data
- curl: show better error message when no homedir is found
- curl: show error for --http3 if libcurl lacks support
- curl_setup_once: consistently use WHILE_FALSE in macros
- define: remove HAVE_ENGINE_LOAD_BUILTIN_ENGINES, not used anymore
- docs: Change 'experiemental' to 'experimental'
- docs: TLS SRP doesn't work with TLS 1.3
- docs: fix several typos
- docs: mention CURL_MAX_INPUT_LENGTH restrictions
- doh: improved both encoding and decoding
- doh: make it behave when built without proxy support
- examples/postinmemory.c: Call curl_global_cleanup always
- examples/url2file.c: corrected erroneous comment
- examples: add multi-poll.c
- global_init: undo the "intialized" bump in case of failure
- hostip: suppress compiler warning
- http_ntlm: Remove duplicate NSS initialisation
- lib: Move lib/ssh.h -> lib/vssh/ssh.h
- lib: fix compiler warnings with `CURL_DISABLE_VERBOSE_STRINGS`
- lib: fix warnings found when porting to NuttX
- lib: remove ASSIGNWITHINCONDITION exceptions, use our code style
- lib: remove erroneous +x file permission on some c files
- libssh2: add support for ECDSA and ed25519 knownhost keys
- multi.h: remove INITIAL_MAX_CONCURRENT_STREAMS from public header
- multi: free sockhash on OOM
- multi_poll: avoid busy-loop when called without easy handles attached
- ngtcp2: Support the latest update key callback type
- ngtcp2: fix thread-safety bug in error-handling
- ngtcp2: free used resources on disconnect
- ngtcp2: handle key updates as ngtcp2 master branch tells us
- ngtcp2: increase QUIC window size when data is consumed
- ngtcp2: use overflow buffer for extra HTTP/3 data
- ntlm: USE_WIN32_CRYPTO check removed to get USE_NTLM2SESSION set
- ntlm_wb: fix double-free in OOM
- openssl: Revert to less sensitivity for SYSCALL errors
- openssl: improve error message for SYSCALL during connect
- openssl: prevent recursive function calls from ctx callbacks
- openssl: retrieve reported LibreSSL version at runtime
- openssl: set X509_V_FLAG_PARTIAL_CHAIN by default
- parsedate: offer a getdate_capped() alternative
- pause: avoid updating socket if done was already called
- projects: Fix Visual Studio projects SSH builds
- projects: Fix Visual Studio wolfSSL configurations
- quiche: reject HTTP/3 headers in the wrong order
- remove_handle: clear expire timers after multi_done()
- runtests: --repeat=[num] to repeat tests
- runtests: introduce --shallow to reduce huge torture tests
- schannel: fix --tls-max for when min is --tlsv1 or default
- setopt: Fix ALPN / NPN user option when built without HTTP2
- strerror: Add Curl_winapi_strerror for Win API specific errors
- strerror: Fix an error looking up some Windows error strings
- strerror: Fix compiler warning "empty expression"
- system.h: fix for MCST lcc compiler
- test/sws: search for "Testno:" header unconditionally if no testno
- test1175: verify symbols-in-versions and libcurl-errors.3 in sync
- test1270: a basic -w redirect_url test
- test1456: remove the use of a fixed local port number

test1558: use double slash after file:
- test1560: require IPv6 for IPv6 aware URL parsing
- tests/lib1557: fix mem-leak in OOM
- tests/lib1559: fix mem-leak in OOM
- tests/lib1591: free memory properly on OOM, in the trailers callback
- tests/unit1607: fix mem-leak in OOM
- tests/unit1609: fix mem-leak in OOM
- tests/unit1620: fix bad free in OOM
- tests: Change NTLM tests to require SSL
- tests: Fix bounce requests with truncated writes
- tests: fix build with `CURL_DISABLE_DOH`
- tests: fix permissions of ssh keys in WSL
- tests: make it possible to set executable extensions
- tests: make sure checksrc runs on header files too
- tests: set LC_ALL=en_US.UTF-8 instead of blank in several tests
- tests: use DoH feature for DoH tests
- tests: use rn for log messages in WSL
- tool_operate: fix mem leak when failed config parse
- travis: Fix error detection
- travis: abandon coveralls, it is not reliable
- travis: build ngtcp2 with --enable-lib-only
- travis: export the CC/CXX variables when set
- vtls: make BearSSL possible to set with CURL_SSL_BACKEND
- winbuild: Define CARES_STATICLIB when WITH_CARES=static
- winbuild: Document CURL_STATICLIB requirement for static libcurl