Vs warnings

Fix all warnings on MS VC, also fix 1 bug found by analyzing MS VC warning output.

tested on linux send/receive

added 15 commits

• 804b343a - Visual studio: ssize_t undefined
• aec50044 - Windows: rist.c replace getpid with GetCurrentProcessId
• 8a44f9f8 - Windows disable some warnings
• 05c9825a - Merge branch 'master' of code.videolan.org:rist/librist
• 8887a9c3 - BUGFix: windows be32toh misdefined as htons, should be htonl
• d21945e6 - Further reduce warnings on VS
• 58a76cb3 - We don't depend on uin16_t wraparound
• 401df999 - CI build failing on MacOS and mingw
• 82e1fc74 - CI build failing MacOS
• 2aeb1d87 - Got rid of all warnings on VS
• c6808ee6 - Ifdef msvc pragma
• 56f32642 - Fix VS compilation regression after libevsocket refactoring
• e9a51e34 - Don't break MacOS CI
• 2f40501a - Last warning on MSVC
• 627c3834 - Merge branch 'vs-warnings' of code.videolan.org:rist/librist into vs-warnings

Compare with previous version

unmarked as a Work In Progress

merged