Dumping compiler definitions

Allegedly, giving the gcc compiler the options “-E -dM” will make it dump out all the #define definitions it knows. I tried putting this into a target_compile_options but it did not seem to have any effect. This is cross-compiling for an ARM microprocessor if that makes any difference, but I expect the preprocessor to be the same.

target_compile_options( FreeRTOS PRIVATE
  # Dump symbols
  -E -dM

This did work earlier for the “-save-temps” option.