Instead of having an odd fake of it. Will help some required
refactorings and already showed some issues, fixed by this patch,
namely:

• don't use string(regex replace) to extract a string from another

string. in case it doesn't match it will offer the whole content which
is never what we want.

• messages(ERROR), the correct parameter is FATAL_ERROR, cmake

understands "ERROR" as mere output string

• turn the macro into a function, otherwise 2 calls in the same

subdirectory are dangerous.

CCBUG: 371562

tests still pass, projects that use the macro still build