all: remove unnecessary return after skipping test

testing.Skip{,f} will exit the test via runtime.Goexit. Thus, the
successive return is never reached and can be removed.

Change-Id: I1e399f3d5db753ece1ffba648850427e1b4be300
Reviewed-on: https://go-review.googlesource.com/74990
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

src/go/internal/gccgoimporter/gccgoinstallation_test.go

@@ -152,7 +152,6 @@ func TestInstallationImporter(t *testing.T) {
 	// were compiled with gccgo.
 	if runtime.Compiler != "gccgo" {
 		t.Skip("This test needs gccgo")
-		return
 	}
 
 	var inst GccgoInstallation

src/go/internal/gccgoimporter/importer_test.go

@@ -122,7 +122,6 @@ func TestObjImporter(t *testing.T) {
 	// were compiled with gccgo.
 	if runtime.Compiler != "gccgo" {
 		t.Skip("This test needs gccgo")
-		return
 	}
 
 	tmpdir, err := ioutil.TempDir("", "")

src/runtime/pprof/pprof_test.go

@@ -179,7 +179,6 @@ func testCPUProfile(t *testing.T, need []string, f func(dur time.Duration)) {
 
 	if badOS[runtime.GOOS] {
 		t.Skipf("ignoring failure on %s; see golang.org/issue/13841", runtime.GOOS)
-		return
 	}
 	// Ignore the failure if the tests are running in a QEMU-based emulator,
 	// QEMU is not perfect at emulating everything.
@@ -187,7 +186,6 @@ func testCPUProfile(t *testing.T, need []string, f func(dur time.Duration)) {
 	// IN_QEMU=1 indicates that the tests are running in QEMU. See issue 9605.
 	if os.Getenv("IN_QEMU") == "1" {
 		t.Skip("ignore the failure in QEMU; see golang.org/issue/9605")
-		return
 	}
 	t.FailNow()
 }