After fixing the patch and trying to build again, I'm getting the same build error relating to patch 3 - "03_vista_turn_off_dashes.patch", which is a fix for bug 183646.
If you're able, you may want to help Albin and others figure out the problem.
In the meantime if you're trying to build on windows either don't apply patch 3, or using the master patch file and Tortoise, don't select the 3 gdl related patches; - src\libgdl\gdl-dock-master.c - src\libgdl\gdl-win32.c - src\libgdl\gdl-win32.h
If you try to revert using Tortoise, it won't show anything for the last two, because they are complete new files rather than patches to existing files in the codebase. Therefore Tortoise doesn't consider that those files have changed from the codebase. You will have to delete or rename them yourself.