configure/CMakeLists.txt: Remove C compiler version output
We don't require a C compiler anymore since b256481c (CMakeLists.txt: Specify more properties for top-level project, 2023-08-03) so the version number is always an empty string.
We don't require a C compiler anymore since b256481c (CMakeLists.txt: Specify more properties for top-level project, 2023-08-03) so the version number is always an empty string.