[Linuxsampler-devel] More patches for fixing MSVC compilation for libgig after 4.4.0 release

[Ross M. <mrr...@gm...>]

Hello again. I tried to build libgig 4.4.0 on MSVC and found a few build
errors.

1. I had to define `ssize_t` again in `gig.h`, I previously did this in
`serialization.h`.
2. In `RIFF.h`, line 1972, there seems to be a C++ 20 specific syntax
wrapped in an if `_MSC_VER`, which I fixed by forcing cmake to use C++ 20
for MSVC alone.

note : We use cmake 3.1 but there seems to be a deprecation warning for
cmake < 3.5. Might as well note it. Not sending the patch for that one
right now as it doesn't break compilation.