Keith Ballard authored Nov 20, 2019 and Brad King committed Nov 20, 2019

Previously, if a CMake project requests a component for a language that is
not enabled, it would simply give an error with the message

    Could NOT find MPI (missing: MPI_${LANG}_FOUND)

which is not indicative that the language was not enabled.  This change
provides an error message indicating that it failed to find the
particular MPI component because no compiler was available for the
language and the language might need to be enabled for the project.

Closes: #19996