[tree-ssa] RFC: Never gimplify ASM_EXPRs

[Andrew Haley]

Jason Merrill writes:
 > Andrew and I discussed this issue at the summit, and agreed (I thought)
 > that the asm should either make the operand an input/output operand or pass
 > in X and do the dereference in the explicit assembly.

Fair enough, but the expansion is copying the mem into a local.  We
agreed that this was unnecessary and should be nuked if only for
efficiency's sake, did we not?

Andrew.