cmd/objdump: disable unsupported tests on riscv64

Updates #27532, #36738 and #36739.

Change-Id: If10031c6fd2c8ec2aa8c37f7edb148d8f26f8697
Reviewed-on: https://go-review.googlesource.com/c/go/+/216258


Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/objdump/objdump_test.go

@@ -168,6 +168,8 @@ func TestDisasm(t *testing.T) {
 	switch runtime.GOARCH {
 	case "mips", "mipsle", "mips64", "mips64le":
 		t.Skipf("skipping on %s, issue 12559", runtime.GOARCH)
+	case "riscv64":
+		t.Skipf("skipping on %s, issue 36738", runtime.GOARCH)
 	case "s390x":
 		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
 	}
@@ -176,7 +178,7 @@ func TestDisasm(t *testing.T) {
 
 func TestDisasmCode(t *testing.T) {
 	switch runtime.GOARCH {
-	case "mips", "mipsle", "mips64", "mips64le", "s390x":
+	case "mips", "mipsle", "mips64", "mips64le", "riscv64", "s390x":
 		t.Skipf("skipping on %s, issue 19160", runtime.GOARCH)
 	}
 	testDisasm(t, true)
@@ -192,6 +194,8 @@ func TestDisasmExtld(t *testing.T) {
 		t.Skipf("skipping on %s, no support for external linking, issue 9038", runtime.GOARCH)
 	case "mips64", "mips64le", "mips", "mipsle":
 		t.Skipf("skipping on %s, issue 12559 and 12560", runtime.GOARCH)
+	case "riscv64":
+		t.Skipf("skipping on %s, no support for external linking, issue 36739", runtime.GOARCH)
 	case "s390x":
 		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
 	}
@@ -205,6 +209,8 @@ func TestDisasmGoobj(t *testing.T) {
 	switch runtime.GOARCH {
 	case "mips", "mipsle", "mips64", "mips64le":
 		t.Skipf("skipping on %s, issue 12559", runtime.GOARCH)
+	case "riscv64":
+		t.Skipf("skipping on %s, issue 36738", runtime.GOARCH)
 	case "s390x":
 		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
 	}