Move build-constraints near the top.

text/fuzz.go

@@ -11,13 +11,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// Build only when actually fuzzing
+// +build gofuzz
+
 package text
 
 import "bytes"
 
-// Build only when actually fuzzing
-// +build gofuzz
-
 // Fuzz text metric parser with with github.com/dvyukov/go-fuzz:
 // 
 //     go-fuzz-build github.com/prometheus/client_golang/text