Successful first build and test under MSYS2/mingw64. Thanks for this.

[asctime]

I am so relieved to see someone actually do this.
Compiled so much more easily, and the results were much more useable.

So far just a couple of notes specific to building under recent mingw64(MSYS2 distro):

Unlike Vanilla Windows, mingw64 uses a default prefix:
/MSYS2/mingw64

Had to dig a couple of minutes to find some important but hidden settings:
OMNIORB_CONFIG_DEFAULT_LOCATION
OMNINAMES_LOG_DEFAULT_LOCATION

also adjusted codegen.cmake Line 29:
set(PATH_ENV PATH=\"${PATH_ENV}\")
to prevent

[  5%] Processing Naming.idl..
cmake -E env: no command given
/bin/sh: D:/Download/MinGW-64-souorce/omniORB-cmake-master/mingw64/bin: Is a directory
make[2]: *** [CMakeFiles/RunGenerator.dir/build.make:110: generated/lib/omniORB/omniORB4/Naming.hh] Error 126

(btw declaring PYTHONHOME is redundant as MSYS2-mingw64 python is already seated)
Overall looks great, I am going to refer this fork to the MSYS2 team.