I replaced more lib32/bin32/obj32 with the PlatformArchitecture macro/environment variable and it works for a complete 64-bit build of WinCairo without breaking anything, and it's a huge step in the right direction for the AppleWin port. I had to export PlatformArchitecture to get it to work with the makefiles, which pass it to the bash scripts as a command line parameter.
Created attachment 209303 [details]
Comment on attachment 209303 [details]
Re-opened since this is blocked by bug 120147
Re-closing. These changes were landed in a follow-up issue to Bug 120147.