Fix assorted memory leaks.

Per Coverity (not that any of these are so non-obvious that they should not
have been caught before commit).  The extent of leakage is probably minor
to unnoticeable, but a leak is a leak.  Back-patch as necessary.

Michael Paquier

src/bin/pg_basebackup/streamutil.c

@@ -414,6 +414,7 @@ DropReplicationSlot(PGconn *conn, const char *slot_name)
 		return false;
 	}
 
+	destroyPQExpBuffer(query);
 	PQclear(res);
 	return true;
 }

src/bin/pg_dump/pg_dump.c

@@ -6660,6 +6660,7 @@ getTransforms(Archive *fout, int *numTransforms)
 			appendPQExpBuffer(&namebuf, "%s %s",
 							  typeInfo->dobj.name, lanname);
 		transforminfo[i].dobj.name = namebuf.data;
+		free(lanname);
 	}
 
 	PQclear(res);
@@ -15731,6 +15732,7 @@ getExtensionMembership(Archive *fout, DumpOptions *dopt, ExtensionInfo extinfo[]
 		addObjectDependency(&contable->dataObj->dobj,
 							reftable->dataObj->dobj.dumpId);
 	}
+	PQclear(res);
 	destroyPQExpBuffer(query);
 }
 

src/bin/pg_rewind/libpq_fetch.c

@@ -81,6 +81,7 @@ libpqConnect(const char *connstr)
 
 /*
  * Runs a query that returns a single value.
+ * The result should be pg_free'd after use.
  */
 static char *
 run_simple_query(const char *sql)
@@ -123,6 +124,8 @@ libpqGetCurrentXlogInsertLocation(void)
 
 	result = ((uint64) hi) << 32 | lo;
 
+	pg_free(val);
+
 	return result;
 }
 
@@ -201,6 +204,7 @@ libpqProcessFileList(void)
 
 		process_source_file(path, type, filesize, link_target);
 	}
+	PQclear(res);
 }
 
 /*----

src/bin/scripts/vacuumdb.c

@@ -412,6 +412,7 @@ vacuum_one_database(const char *dbname, vacuumingOptions *vacopts,
 			concurrentCons = ntups;
 		if (concurrentCons <= 1)
 			parallel = false;
+		PQclear(res);
 	}
 
 	/*