cmd/compile: fix ssa/check/on build

Disable phielimValue from rewrite pass for now.

Change-Id: I9f3bb1f527b50bc7a21cc6b7cb89f6136efd81e8
Reviewed-on: https://go-review.googlesource.com/22335
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/rewrite.go

@@ -40,8 +40,6 @@ func applyRewrite(f *Func, rb func(*Block) bool, rv func(*Value, *Config) bool)
 			}
 			curb = nil
 			for _, v := range b.Values {
-				change = phielimValue(v) || change
-
 				// Eliminate copy inputs.
 				// If any copy input becomes unused, mark it
 				// as invalid and discard its argument. Repeat