[AD] allegro (image addon) build on 64-bit windows

[Peter Hull <peterhull90@xxxxxxxxxx>]

I tried to build Allegro on 64 bit windows and it fails because it can't find the correct GDI+ library.

I am configuring like this:
> cmake -A x64 path-to-allegro-source

And get 18 link errors, the first of which is:
gdiplus.obj : error LNK2019: unresolved external symbol GdipAlloc

The problem seems to be that CMake can only look for the 32-bit version of GDIplus.lib because the Windows SDK puts the 32/64 bit libs in directories that don't match the pattern that CMake expects.

I asked on Stack overflow:
http://stackoverflow.com/questions/33124745/cmake-finding-32bit-gdi-on-64-bit-platform

 and also on the cmake ML:
http://public.kitware.com/pipermail/cmake/2015-October/061804.html

There was not a great response but a suggested workaround from Sergey.

Unless anyone else has some brighter idea I can submit a patch for this but I'd like to know - does the currect code work OK on MinGW (is there such a thing as 64-bit MinGW?)

Thanks,

Pete

ps, Siegelord when I fix this I can send in the final Nuget package script for your allegro_winpkg repo! Promise!!