Only initialize CMAKE_CXX_COMPILER_PREDEFINES_COMMAND

Don't initialize the other CMAKE_<LANG>_COMPILER_PREDEFINES_COMMAND
variables.

The only language variant that is used is
CMAKE_CXX_COMPILER_PREDEFINES_COMMAND, and the other language variants
contained invalid, namely C++-specific commands.

Fixes: #23968
9 files changed