Cleaned up gccgo error messages require minor adjustment to

test.

const1.go:27: error: integer constant overflow
const1.go:29: error: integer constant overflow
const1.go:30: error: integer constant overflow
const1.go:31: error: integer constant overflow
const1.go:32: error: integer constant overflow
const1.go:33: error: integer constant overflow
const1.go:33: error: integer constant overflow
const1.go:34: error: integer constant overflow
const1.go:37: error: integer constant overflow
const1.go:38: error: integer constant overflow
const1.go:40: error: integer constant overflow
const1.go:41: error: integer constant overflow
const1.go:43: error: integer constant overflow
const1.go:44: error: integer constant overflow
const1.go:45: error: integer constant overflow
const1.go:48: error: integer constant overflow
const1.go:50: error: integer constant overflow
const1.go:51: error: integer constant overflow
const1.go:52: error: integer constant overflow
const1.go:53: error: integer constant overflow
const1.go:55: error: integer constant overflow
const1.go:56: error: division by zero
const1.go:59: error: floating point constant overflow
const1.go:61: error: floating point constant overflow
const1.go:62: error: division by zero
const1.go:47: error: integer constant overflow
const1.go:49: error: integer constant overflow
const1.go:60: error: floating point constant overflow
const1.go:68: error: argument 1 has incompatible type (cannot use type int8 as type int)
const1.go:69: error: argument 1 has incompatible type (cannot use type int8 as type int)
const1.go:70: error: argument 1 has incompatible type (cannot use type uint8 as type int)
const1.go:72: error: argument 1 has incompatible type (cannot use type float32 as type int)
const1.go:73: error: argument 1 has incompatible type (cannot use type float as type int)
const1.go:74: error: floating point constant truncated to integer
const1.go:76: error: argument 1 has incompatible type (cannot use type float64 as type int)
const1.go:77: error: argument 1 has incompatible type
const1.go:78: error: argument 1 has incompatible type

R=rsc
http://go/go-review/1022001

test/const1.go

@@ -74,6 +74,6 @@ func main() {
 	f(ConstFloat);	// ERROR "truncate"
 	f(ConstFloat - 0.5);	// OK
 	f(Big);	// ERROR "convert|wrong type|cannot"
-	f(String);	// ERROR "convert|wrong type|cannot"
-	f(Bool);	// ERROR "convert|wrong type|cannot"
+	f(String);	// ERROR "convert|wrong type|cannot|incompatible"
+	f(Bool);	// ERROR "convert|wrong type|cannot|incompatible"
 }