Fortran: -fc-prototypes, deferred shape and deferred length dummies [PR125902]

	PR fortran/125902

gcc/fortran/ChangeLog:

	* dump-parse-tree.cc (get_c_type_name): Use CFI_cdesc_t also for
	deferred shape and deferred length dummies, as well as for
	assumed-length scalar character dummies.

gcc/testsuite/ChangeLog:

	* gfortran.dg/c-prototypes_1.F90: New test.

(cherry picked from commit e782cebd83be590090216ce3642318f9121991ce)