test: match gccgo error messages

bug340.go:14:7: error: expected type
bug340.go:15:4: error: reference to undefined field or method ‘x’

bug350.go:12:1: error: redefinition of ‘m’
bug350.go:11:1: note: previous definition of ‘m’ was here
bug350.go:15:1: error: redefinition of ‘p’
bug350.go:14:1: note: previous definition of ‘p’ was here

bug351.go:12:6: error: non-name on left side of ‘:=’

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5127041

test/fixedbugs/bug340.go

@@ -10,8 +10,8 @@ package main
 
 func main() {
 	var x interface{}
-	switch t := x.(type) { // ERROR "0 is not a type"
-	case 0:
-		t.x = 1 // ERROR "type interface \{ \}"
+	switch t := x.(type) { // GC_ERROR "0 is not a type"
+	case 0:		// GCCGO_ERROR "expected type"
+		t.x = 1 // ERROR "type interface \{ \}|reference to undefined field or method"
 	}
 }

test/fixedbugs/bug350.go

@@ -8,8 +8,8 @@ package main
 
 type T int
 
-func (T) m() {}
-func (T) m() {} // ERROR "T[.]m redeclared"
+func (T) m() {} // GCCGO_ERROR "previous"
+func (T) m() {} // ERROR "T[.]m redeclared|redefinition"
 
-func (*T) p() {}
-func (*T) p() {} // ERROR "[(][*]T[)][.]p redeclared"
+func (*T) p() {} // GCCGO_ERROR "previous"
+func (*T) p() {} // ERROR "[(][*]T[)][.]p redeclared|redefinition"

test/fixedbugs/bug351.go

@@ -9,5 +9,5 @@ package main
 var x int
 
 func main() {
-	(x) := 0  // ERROR "non-name [(]x[)]"
+	(x) := 0  // ERROR "non-name [(]x[)]|non-name on left side"
 }