HaikuDepot: SDL2 cannot work with CMake

[Carlo_Bramini]

I updated my packages with HaikuDepot application. The process updated SDL2 from 2.0.20 to 2.26.4 and I discovered that the development package doesn't work anymore with CMake.

Running a simple script prints this message on the console:

CMake Error at /boot/system/lib/cmake/SDL2/SDL2mainTargets.cmake:80 (message):
  The imported target "SDL2::SDL2main" references the file

     "/boot/system/lib/libSDL2main.a"

  but this file does not exist.  Possible reasons include:

  * The file was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and contained

     "/boot/system/lib/cmake/SDL2/SDL2mainTargets.cmake"

  but not all the files it references.

Call Stack (most recent call first):
  /boot/system/lib/cmake/SDL2/SDL2Config.cmake:49 (include)
  CMakeLists.txt:18 (find_package)

Actually, CMake is right because I have found that static library installed here:

/boot/system/develop/lib/libSDL2main.a

Manually fixing the issue by making a link to /boot/system/lib/libSDL2main.a didn't work because it prints that the filesystem is read-only, but I think that there is something else to do.