perf scripts python: exported-sql-viewer.py: Fix warning display

Deprecation warnings are useful only for the developer, not an end user.
Display warnings only when requested using the python -W option. This
stops the display of warnings like:

tools/perf/scripts/python/exported-sql-viewer.py:5102: DeprecationWarning:
an integer is required (got type PySide2.QtCore.Qt.AlignmentFlag).
Implicit conversion to integers using __int__ is deprecated, and
may be removed in a future version of Python.
err = app.exec_()

Since the warning can be fixed only in PySide2, we must wait for it to
be finally fixed there.

Signed-off-by: Adrian Hunter <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: [e-mail] # v5.3+
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

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

···
 from __future__ import print_function
 
 import sys
+# Only change warnings if the python -W option was not used
+if not sys.warnoptions:
+	import warnings
+	# PySide2 causes deprecation warnings, ignore them.
+	warnings.filterwarnings("ignore", category=DeprecationWarning)
 import argparse
 import weakref
 import threading