perf script: Fix postgresql ubuntu install instructions

The current instructions for setting up an Ubuntu system for using the
export-to-postgresql.py script are incorrect.

The instructions in the script have been updated to work on newer
versions of ubuntu.

-Add missing dependencies to apt-get command:
    python-pyside.qtsql, libqt4-sql-psql
-Add '-s' option to createuser command to force the user to be a
    superuser since the command doesn't prompt as indicated in the
    current instructions.

Tested on: Ubuntu 14.04, Ubuntu 16.04(beta)
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1461056164-14914-3-git-send-email-cphlipot0@gmail.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/scripts/python/export-to-postgresql.py

@@ -34,10 +34,9 @@ import datetime
 #
 # ubuntu:
 #
-#	$ sudo apt-get install postgresql
+#	$ sudo apt-get install postgresql python-pyside.qtsql libqt4-sql-psql
 #	$ sudo su - postgres
-#	$ createuser <your user id here>
-#	Shall the new role be a superuser? (y/n) y
+#	$ createuser -s <your user id here>
 #
 # An example of using this script with Intel PT:
 #