FLTK MinGW Libs

[Saito720]

Replaced 6 existing FLTK libraries with MinGW builds.

[jkulawik]

Don't replace the win32 libs because that will screw up MSVC builds if we decide to use those at some point. Instead place the new ones in dependencies/precompiled/lib/mingw32 and we will set the precompiled lib dir to that for MinGW.

It won't compile that way at the moment, so you can still use a mixed folder locally.

To make it work we will have to either use both folders and prioritize mingw32 over win32 in find functions (if that's doable at all) or just make the functions search one of them on a case-by-case basis. I will look into it later

[jkulawik]

as to setting the path, all you need is to add this part to BoilerPlate:

     set(PLATFORM_PREFIX "win32")
+    if(MINGW)
+        set(PLATFORM_PREFIX "mingw32")
+    endif()

[jkulawik]

Also, are all of those actually needed? Launcher seems to only import fltk, fltkimages and fltkjpg