cmd/goyacc: merge variable declaration with assignment

Found with honnef.co/go/tools/cmd/simple.

Change-Id: I04c65394f1c6404f57bb2088353325899f35011f
Reviewed-on: https://go-review.googlesource.com/38177
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
diff --git a/cmd/goyacc/yacc.go b/cmd/goyacc/yacc.go
index 7db1cb1..fdf8156 100644
--- a/cmd/goyacc/yacc.go
+++ b/cmd/goyacc/yacc.go
@@ -1225,9 +1225,7 @@
 // skipcom is called after reading a '/'
 //
 func skipcom() int {
-	var c rune
-
-	c = getrune(finput)
+	c := getrune(finput)
 	if c == '/' {
 		for c != EOF {
 			if c == '\n' {