cmd/5g etc: mechanical cleanup

Run rsc.io/grind rev 796d0f2 on C->Go conversions.

This replaces various awkward := initializations with plain var declarations.

Checked bit-for-bit compatibility with toolstash + buildall.

Change-Id: I601101d8177894adb9b0e3fb55dfe0ed4f544716
Reviewed-on: https://go-review.googlesource.com/6517
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/cmd/8g/ggen.go b/src/cmd/8g/ggen.go
index 27938c7..1cc9a2b 100644
--- a/src/cmd/8g/ggen.go
+++ b/src/cmd/8g/ggen.go
@@ -253,7 +253,7 @@
 
 	case 1, // call in new proc (go)
 		2: // deferred call (defer)
-		stk := gc.Node{}
+		var stk gc.Node
 
 		stk.Op = gc.OINDREG
 		stk.Val.U.Reg = i386.REG_SP
@@ -429,7 +429,7 @@
 		gc.Fatal("cgen_callret: nil")
 	}
 
-	nod := gc.Node{}
+	var nod gc.Node
 	nod.Op = gc.OINDREG
 	nod.Val.U.Reg = i386.REG_SP
 	nod.Addable = 1
@@ -456,7 +456,7 @@
 		gc.Fatal("cgen_aret: nil")
 	}
 
-	nod1 := gc.Node{}
+	var nod1 gc.Node
 	nod1.Op = gc.OINDREG
 	nod1.Val.U.Reg = i386.REG_SP
 	nod1.Addable = 1
@@ -565,7 +565,7 @@
 	}
 	gmove(&t2, &n1)
 	gmove(&t1, ax)
-	p2 := (*obj.Prog)(nil)
+	var p2 *obj.Prog
 	var n4 gc.Node
 	if gc.Nacl {
 		// Native Client does not relay the divide-by-zero trap
@@ -709,7 +709,7 @@
 		return
 	}
 
-	oldcx := gc.Node{}
+	var oldcx gc.Node
 	var cx gc.Node
 	gc.Nodreg(&cx, gc.Types[gc.TUINT32], i386.REG_CX)
 	if reg[i386.REG_CX] > 1 && !gc.Samereg(&cx, res) {