all: protect alloc count tests by -testing.short

Update #5000
Should reduce the flakiness a little. Malloc counting is important
to general testing but not to the build dashboard, which uses -short.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/12866047
diff --git a/src/pkg/path/path_test.go b/src/pkg/path/path_test.go
index 69caa80..13b5852 100644
--- a/src/pkg/path/path_test.go
+++ b/src/pkg/path/path_test.go
@@ -72,7 +72,12 @@
 			t.Errorf("Clean(%q) = %q, want %q", test.result, s, test.result)
 		}
 	}
+}
 
+func TestCleanMallocs(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping malloc count in short mode")
+	}
 	if runtime.GOMAXPROCS(0) > 1 {
 		t.Log("skipping AllocsPerRun checks; GOMAXPROCS>1")
 		return