CMake: Add the resource files to the Cygwin and MSYS2 builds

CMake: Add the resource files to the Cygwin and MSYS2 builds

Autotools-based build has always done this so this is for consistency.

However, the CMake build won't create the DEF file when building
for Cygwin or MSYS2 because in that context it should be useless.
(If Cygwin or MSYS2 is used to host building of normal Windows
binaries then the DEF file is still created.)

(cherry picked from commit c3b9dad07d3fd9319f88386b7095019bcea45ce1)