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/cgen.go b/src/cmd/8g/cgen.go
index a2bd6ec..93934fb 100644
--- a/src/cmd/8g/cgen.go
+++ b/src/cmd/8g/cgen.go
@@ -622,7 +622,7 @@
 		agen(&n1, res)
 
 	case gc.OINDEX:
-		p2 := (*obj.Prog)(nil) // to be patched to panicindex.
+		var p2 *obj.Prog // to be patched to panicindex.
 		w := uint32(n.Type.Width)
 		bounded := gc.Debug['B'] != 0 || n.Bounded
 		var n3 gc.Node
@@ -1005,7 +1005,7 @@
 	}
 
 	nl := n.Left
-	nr := (*gc.Node)(nil)
+	var nr *gc.Node
 
 	if nl != nil && gc.Isfloat[nl.Type.Etype] {
 		bgen_float(n, bool2int(true_), likely, to)
diff --git a/src/cmd/8g/cgen64.go b/src/cmd/8g/cgen64.go
index f0b9e49..5235270 100644
--- a/src/cmd/8g/cgen64.go
+++ b/src/cmd/8g/cgen64.go
@@ -236,7 +236,7 @@
 
 		// load shift value into register.
 		// if high bits are set, zero value.
-		p1 := (*obj.Prog)(nil)
+		var p1 *obj.Prog
 
 		if gc.Is64(r.Type) {
 			gins(i386.ACMPL, &hi2, ncon(0))
@@ -337,7 +337,7 @@
 
 		// load shift value into register.
 		// if high bits are set, zero value.
-		p1 := (*obj.Prog)(nil)
+		var p1 *obj.Prog
 
 		if gc.Is64(r.Type) {
 			gins(i386.ACMPL, &hi2, ncon(0))
@@ -529,7 +529,7 @@
 		regfree(&rr)
 	}
 
-	br := (*obj.Prog)(nil)
+	var br *obj.Prog
 	switch op {
 	default:
 		gc.Fatal("cmp64 %v %v", gc.Oconv(int(op), 0), gc.Tconv(t, 0))
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) {
diff --git a/src/cmd/8g/gsubr.go b/src/cmd/8g/gsubr.go
index 0d26a41..6931ea8 100644
--- a/src/cmd/8g/gsubr.go
+++ b/src/cmd/8g/gsubr.go
@@ -1842,8 +1842,8 @@
 		}
 	}
 
-	af := obj.Addr{}
-	at := obj.Addr{}
+	var af obj.Addr
+	var at obj.Addr
 	if f != nil {
 		gc.Naddr(f, &af, 1)
 	}