tree-ssa-forwprop.c (simplify_builtin_call): Do not remove stmt at gsi_p, instead replace it with a NOP removed later.

2019-08-16  Richard Biener  <rguenther@suse.de>

	* tree-ssa-forwprop.c (simplify_builtin_call): Do not remove
	stmt at gsi_p, instead replace it with a NOP removed later.
	(pass_forwprop::execute): Fully propagate lattice, DCE stmts
	that became dead because of that.

	fortran/
	* trans-intrinsic.c (gfc_conv_intrinsic_findloc): Initialize
	forward_branch to avoid bogus uninitialized warning.

	* gcc.dg/tree-ssa/forwprop-31.c: Adjust.

From-SVN: r274563