Fortran: reject MODULE PROCEDURE outside generic module interface [PR99036]

gcc/fortran/ChangeLog:

	PR fortran/99036
	* decl.cc (gfc_match_modproc): Reject MODULE PROCEDURE if not in a
	generic module interface.

gcc/testsuite/ChangeLog:

	PR fortran/99036
	* gfortran.dg/pr99036.f90: New test.