devel/cmake-core: Fixup 76b8901dae25efc80678bb950

Despite switching to an out-of-source build, .bak and .orig files were
still being pattern matched and installed into STAGEDIR. These were never
packaged nor installed on the system, however, so this is a no-op to the
end-user.

MFH: 2024Q4
(cherry picked from commit 22bf11bc9c8d83deb30f7084d31b9f7a5ad261d1)