cmd/compile: remove traces of old register allocator

Only added lines are moving amd64 and x86's ginsnop functions from
gsubr.go to ggen.go to match other architectures, so all of the
gsubr.go files can go away.

Change-Id: Ib2292460c155ae6d9dcf5c9801f178031d8eea7a
Reviewed-on: https://go-review.googlesource.com/29240
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index f469694..b44ad19 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -355,18 +355,9 @@
 type Arch struct {
 	LinkArch *obj.LinkArch
 
-	REGSP        int
-	REGCTXT      int
-	REGCALLX     int // BX
-	REGCALLX2    int // AX
-	REGRETURN    int // AX
-	REGMIN       int
-	REGMAX       int
-	REGZERO      int // architectural zero register, if available
-	FREGMIN      int
-	FREGMAX      int
-	MAXWIDTH     int64
-	ReservedRegs []int
+	REGSP    int
+	REGCTXT  int
+	MAXWIDTH int64
 
 	Betypeinit func()
 	Defframe   func(*obj.Prog)