cmd/gc: run escape analysis always (even in -N mode)
Fixes #8585.
Removes some little-used code paths.
LGTM=josharian
R=golang-codereviews, minux, josharian
CC=golang-codereviews, iant, r
https://golang.org/cl/132970043
diff --git a/test/escape2.go b/test/escape2.go
index 28251aa..6a46ce8 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -7,6 +7,8 @@
// Test, using compiler diagnostic flags, that the escape analysis is working.
// Compiles but does not run. Inlining is disabled.
+// escape2n.go contains all the same tests but compiles with -N.
+
package foo
import (
