Apply leaf cleanup to threadz samples

The legacy profilez parser handles duplicate leaf samples that are a
common artifact of satck unwinding. Apply the same technique to threadz
profiles where duplicate samples also occur.

profile/legacy_profile.go

 		}
 	}
 
+	if err := p.ParseMemoryMap(bytes.NewBuffer(b)); err != nil {
+		return nil, err
+	}
+
+	cleanupDuplicateLocations(p)
+	return p, nil
+}
+
+func cleanupDuplicateLocations(p *Profile) {
 	// The profile handler may duplicate the leaf frame, because it gets
 	// its address both from stack unwinding and from the signal
 	// context. Detect this and delete the duplicate, which has been
 			s.Location = append(s.Location[:1], s.Location[2:]...)
 		}
 	}
-
-	if err := p.ParseMemoryMap(bytes.NewBuffer(b)); err != nil {
-		return nil, err
-	}
-	return p, nil
 }
 
 // parseCPUSamples parses a collection of profilez samples from a
 		return nil, err
 	}
 
+	cleanupDuplicateLocations(p)
 	return p, nil
 }