Fix psp-pkg-config --libs output for all libraries

[sharkwouter]

When using psp-pgk-config with the -libs flag, it should return all libraries required for linking to work. This is a big problem for the SDL helper libraries for example.

[sharkwouter]

SDL2 is only missing SDL2main. SDL2_ttf now has support for setting the libraries in the pc file per platform through CMake, the ones for PSP just need to be added.

In a branch for OceanPop where I'm trying to clean up the CMakeLists.txt file by using pkg-config for the PSP build I still need to add the following dependencies manually for it to work:

    if(PSP)
        list(APPEND SDL2_LIBRARIES SDL2main)
        list(APPEND SDL2_MIXER_LIBRARIES vorbisfile vorbis ogg)
        list(APPEND SDL2_IMAGE_LIBRARIES jpeg png z)
        list(APPEND SDL2_TTF_LIBRARIES freetype)

For other libraries I do not know what is needed.

[sharkwouter]

For sdl2-ttf this is now fixed.

[diamant3]

Hello again! Can I try to fix this issue?

[sharkwouter]

Go for it, it would be appreciated. I don't have a list of which ones are wrong, though. Might not be many if we're lucky.