Fix tree-opt/PR106087: ICE with inline-asm with multiple output and assigned only...

Fix tree-opt/PR106087: ICE with inline-asm with multiple output and assigned only static vars

The problem here is that when we mark the ssa name that was referenced in the now removed
dead store (to a write only static variable), the inline-asm would also be removed
even though it was defining another ssa name. This fixes the problem by checking
to make sure that the statement was only defining one ssa name.

Committed as approved after a bootstrapped and tested on x86_64 with no regressions.

	PR tree-optimization/106087

gcc/ChangeLog:

	* tree-ssa-dce.cc (simple_dce_from_worklist): Check
	to make sure the statement is only defining one operand.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/inline-asm-1.c: New test.