* fix MSVC compiler shared library issues - mostly around 'extern const'
* add vcpkg install getopt to appveyor-windows.yml
show appveyor where to get getopt from vcpkg (non-static lib to avoid LGPL violation)
* add missing else case in lsquic_shared_support.h for windows static lib path
* have cmake spit out it's version
have cmake copy dependent dlls to build dir for tests on windows (getopt.dll)
* copy getopt.dll dep for tests
added commented version that requires >= 3.21 but handles any dll deps
* try caching boringssl dir to reduce CI build time since it's always same commit specified in config file
define VCPKG_ROOT in env since I can't seem to find it by VCPKG_ROOT or VCPKG_INSTALLED_DIR in appveyor's cmake v3.16 + vcpkg
* make windows cache dependent on yml and cmd
* sync up with changes to ls-qpack
- [API] New knob to set outgoing packet batch size.
- Aborted connection now become tickable immediately.
- Abort connection when HTTP/3 frame cannot be opened (can only happen
when malloc fails).
- [FEATURE] Update the timestamp extension to latest version.
- [FEATURE] Cope with appearance of ECN blackholes.
- [OPTIMIZATION] return packno offset and size when header is generated.
- [BUGFIX] ignore old ACK frames in mini conns.
- [BUGFIX] Mark initial server path as initialized.
- [BUGFIX] Do not merge ACK if ECN counts do not match.
- Turn incoming packet number history in mini conn back on.
- Record mini conn event history again when compiled in debug mode.
- IETF mini conn: log when ACK is queued.
- Clean up and refactor code in several places.
