Fortran : ICE in gfc_trans_label_assign PR50392

Fortran  : ICE in gfc_trans_label_assign PR50392

A function may contain an assigned goto.  If the the return variable
is an integer a statement can be assigned to it.  Prior to this fix
this resulted in an ICE.

2020-05-28  Tobias Burnus  <tobias@codesourcery.com>

gcc/fortran/

	PR fortran/50392
	* trans-decl.c (gfc_get_symbol_decl): Remove unnecessary block
	delimiters.  Add auxiliary variables if a label is assigned to
	a return variable. (gfc_gat_fake_result): If the symbol has an
	assign attribute set declaration from the symbol's backend
	declaration.

2020-05-28  Mark Eggleston  <markeggleston@gnu.gcc.org>

gcc/testsuite/

	PR fortran/50392
	* gfortran.dg/pr50392.f: New test.

(cherry picked from commit a7fd43c38f7469a3ef5ee30e889d60e1376d4dfc)