internal/gocore: let android builders skip tests calling loadExampleVersion

loadExampleVersion copies and reads example core files, which may be bigger
than what android devices used in builders can handle.

Also, mark helper functions with t.Helper.

Fixes golang/go#34210

Change-Id: I73083cf0e59d928bb84cc1eb9b5b5a80a2e30f31
Reviewed-on: https://go-review.googlesource.com/c/debug/+/197777
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/internal/gocore/gocore_test.go b/internal/gocore/gocore_test.go
index 75d0a39..00f10b4 100644
--- a/internal/gocore/gocore_test.go
+++ b/internal/gocore/gocore_test.go
@@ -29,6 +29,7 @@
 //         _ = *(*int)(nil)
 // }
 func loadExample(t *testing.T) *Process {
+	t.Helper()
 	if runtime.GOOS == "android" {
 		t.Skip("skipping test on android")
 	}
@@ -44,6 +45,10 @@
 }
 
 func loadExampleVersion(t *testing.T, version string) *Process {
+	t.Helper()
+	if runtime.GOOS == "android" {
+		t.Skip("skipping test on android")
+	}
 	if version == "1.9" {
 		version = ""
 	}
@@ -79,6 +84,7 @@
 
 // unzip unpacks the zip file name into the directory dir.
 func unzip(t *testing.T, name, dir string) {
+	t.Helper()
 	r, err := zip.OpenReader(name)
 	if err != nil {
 		t.Fatalf("can't read zip file %s: %s", name, err)