PR fortran/100274 - ICE in gfc_conv_procedure_call, at fortran/trans-expr.c:6131

PR fortran/100274 - ICE in gfc_conv_procedure_call, at fortran/trans-expr.c:6131

When the check for the length of formal and actual character arguments
found a mismatch and emitted a warning, it would skip further checks
like that could lead to errors.  Fix that by continuing the checking.
Also catch a NULL pointer dereference.

gcc/fortran/ChangeLog:

	PR fortran/100274
	* interface.c (gfc_compare_actual_formal): Continue checks after
	emitting warning for argument length mismatch.
	* trans-expr.c (gfc_conv_procedure_call): Check for NULL pointer
	dereference.

gcc/testsuite/ChangeLog:

	PR fortran/100274
	* gfortran.dg/argument_checking_25.f90: New test.

(cherry picked from commit a8b79cc939d6786293f654c42a2d1b0ab040de0e)