This eq-gnu compiler I am using has an x86_64-w64-mingw32 sub folder. So it’s also a MINGW.
Running into error with mutex, I decided to give MinGW a go. I downloaded x86_64-posix-sjlj, also I changed to use MinGW generator. Then I finished build VTK.
Also tried to build a test project like this: Help to Build project under WIn 10 - Support - VTK
After changing the setting of RenderingContextOpenGL2 from DEFAULT to YES, I got the project running. This time I changed it by editing the CMakeCache.txt file.
I think the eq-gnu compiler is the same as x86_64-win32-sjlj, but has a newer version c/c++.