runtime: enable GDB tests on mips64 (except TestGdbPythonCgo)

They were failing when run on 32bit RFS, with 32bit gdb.
(mips64 builder now has 64bit RFS, with gdb 7.9.)
Leaving TestGdbPythonCgo disabled, it behaves as described in #18784.

Fixes #18173

Change-Id: I3c438cd5850b7bfd118ac6396f40c1208bac8c2d
Reviewed-on: https://go-review.googlesource.com/45874Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/runtime-gdb_test.go

@@ -91,16 +91,13 @@ func TestGdbPython(t *testing.T) {
 }
 
 func TestGdbPythonCgo(t *testing.T) {
-	if runtime.GOARCH == "mips" || runtime.GOARCH == "mipsle" {
+	if runtime.GOARCH == "mips" || runtime.GOARCH == "mipsle" || runtime.GOARCH == "mips64" {
 		testenv.SkipFlaky(t, 18784)
 	}
 	testGdbPython(t, true)
 }
 
 func testGdbPython(t *testing.T, cgo bool) {
-	if runtime.GOARCH == "mips64" {
-		testenv.SkipFlaky(t, 18173)
-	}
 	if cgo && !build.Default.CgoEnabled {
 		t.Skip("skipping because cgo is not enabled")
 	}
@@ -258,9 +255,6 @@ func TestGdbBacktrace(t *testing.T) {
 	if runtime.GOOS == "netbsd" {
 		testenv.SkipFlaky(t, 15603)
 	}
-	if runtime.GOARCH == "mips64" {
-		testenv.SkipFlaky(t, 18173)
-	}
 
 	t.Parallel()
 	checkGdbEnvironment(t)
@@ -332,10 +326,6 @@ func main() {
 // TestGdbAutotmpTypes ensures that types of autotmp variables appear in .debug_info
 // See bug #17830.
 func TestGdbAutotmpTypes(t *testing.T) {
-	if runtime.GOARCH == "mips64" {
-		testenv.SkipFlaky(t, 18173)
-	}
-
 	t.Parallel()
 	checkGdbEnvironment(t)
 	checkGdbVersion(t)