[reference] Building Krita 3.0 with TDM-GCC (mingw) on Windows

[Alvin Wong]

Dear all,

Since this had been asked a few times on the irc channel, I think it
would be a good idea to send this to the mailing list for the record.

I had been building Krita 3.0 with TDM64-GCC 5.1 on Windows since Boud
switched to cross-compiling Krita for Window with MXE on Linux. Part
of the process is similar to building with MSVC but some additional
changes had to be made to get it to compile and run properly.

I've put the stuff here:
https://gist.github.com/alvinhochun/429129650a38ecd4b3a1d88ef031bb5e

It's not really well-written and is a bit messy. Also, the patches may
not apply cleanly to the git master branch. To summarize, there is a
main patch to be applied for building Krita with the default vc 0.75
(as of Krita 3.0), and another patch to be applied for building with
vc 1.2 after merging with the `zachmann-vc1-port` branch; there is
also a batch file which roughly outlined the steps I took to build
Krita (the script itself is not designed to be run directly due to
lack of error handling, but individual commands should be copied to a
command prompt and executed one by one,) and another batch file to
strip and package the software.

When installing TDM-GCC, please be sure to also install the OpemMP
package to get the performance boost in gmic. For some reason my CMake
failed to set the OpenMP flags so I have to append
`-DOpenMP_C_FLAGS=-fopenmp -DOpenMP_CXX_FLAGS=-fopenmp` to the CMake
command, but it may be due to me not doing a clean build.

Sorry that I don't have the time to do a proper writeup on the whole
process, but I think this should be sufficient for now.

Best Regards,

Alvin

CC: stuartmd on freenode (used BCC to hide email)