observation:

If you add CMAKE_EXE_LINKER_FLAGS and have a typo (e.g: misspell a lib name), this will cause failures downstream when you get to BLT-builtin TPL support. In my case, finding MPI failed and there was no output that would signal it is related the lib flags, just "I can't find MPI!"

Since these flags are used everywhere, a compile check that uses these flags early could detect an issue and allow us to provide a better error message.