perf scripts python: exported-sql-viewer.py: Use new 'has_calls' column

If the new 'has_calls' column is present, use it with the call graph and
call tree to select only comms that have calls.

Committer testing:

Just started the exported-sql-view.py and accessed all the reports, no
backtraces.

Signed-off-by: Adrian Hunter <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/scripts/python/exported-sql-viewer.py

···
 		super(CallGraphRootItem, self).__init__(glb, params, 0, None)
 		self.dbid = 0
 		self.query_done = True
+		if_has_calls = ""
+		if IsSelectable(glb.db, "comms", columns = "has_calls"):
+			if_has_calls = " WHERE has_calls = TRUE"
 		query = QSqlQuery(glb.db)
-		QueryExec(query, "SELECT id, comm FROM comms")
+		QueryExec(query, "SELECT id, comm FROM comms" + if_has_calls)
 		while query.next():
 			if not query.value(0):
 				continue
···
 		super(CallTreeRootItem, self).__init__(glb, params, 0, None)
 		self.dbid = 0
 		self.query_done = True
+		if_has_calls = ""
+		if IsSelectable(glb.db, "comms", columns = "has_calls"):
+			if_has_calls = " WHERE has_calls = TRUE"
 		query = QSqlQuery(glb.db)
-		QueryExec(query, "SELECT id, comm FROM comms")
+		QueryExec(query, "SELECT id, comm FROM comms" + if_has_calls)
 		while query.next():
 			if not query.value(0):
 				continue