sdl: fix brigthness option on all desktop and windows after minimize

[GermanAizek]

@wolfetplayer The bug is most often detected when the game loads levels and at that moment the game is minimized.

[wolfetplayer]

Error when tryin to build:

LD build/release-mingw64-x86_64/RealRTCW.x64.exe C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: build/release-mingw64-x86_64/client/sdl_input.o:sdl_input.c:(.rdata$.refptr.glConfig[.refptr.glConfig]+0x0): undefined reference to `glConfig' collect2.exe: error: ld returned 1 exit status