`make distcheck` fails on MSYS2 Mingw

[lshprung]

make distcheck fails with error:

windres icon/terminal-media-launcher.rc -O coff -o icon/terminal-media-launcher.res
cc1.exe: fatal error: icon/terminal-media-launcher.rc: No such file or directory
compilation terminated

[lshprung]

A more detailed cause of this issue can be seen when attempting to build outside of the source tree (i.e., in a separate build/ directory). The build will fail when trying to generate the .res file.