Make sure GetMODVersion and its console equiv properly detect failing to get a reply from the MS, also added extra console/menu messages

MinGW: Fix compiling on 64-bit Windows.

See merge request STJr/SRB2!329

Should fix libgme depending on two DLLs externally.

Camera subsector crash fix

See merge request STJr/SRB2!318

OpenGL HUD scaling fix

See merge request STJr/SRB2!320

Fix stringop-truncation: ‘strncpy’ output truncated before terminating nul copying 8 bytes from a string of the same length

Fix =sizeof-pointer-memaccess: argument to ‘sizeof’ in ‘strncpy’ call is the same expression as the source; did you mean to use the size of the destination?

Fix desynch when toggling analog mode or flipcam

Update SDL Mixer to 2.0.4

See merge request STJr/SRB2!322

Update SDL2 to 2.0.9

See merge request STJr/SRB2!321

Remove unnecessary SDLCALL from IMG_xpm.c declarations

See merge request STJr/SRB2!327

Missed #ifdef HAVE_LIBGME in win_snd

See merge request STJr/SRB2!326

mixer_sound fix x64 build issue

See merge request STJr/SRB2!323

Save the current renderer to screenshots.

See merge request STJr/SRB2!324

Fix OpenGL's HUD not being scaled the same way as Software's, by removing an old OpenGL-specific hack for fdupx/fdupy