perf python: Initialize 'page_size' variable

The commit 0c1fe6b:

 'perf tools: Have the page size value available for all tools'

Broke the python binding because the global variable 'page_size' is
initialized on the main() routine, that is not called when using
just the python binding, causing evlist.mmap() to fail because it
expects that variable to be initialized to the system's page size.

Fix it by initializing it on the binding init routine.

Reported-by: David Ahern <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: acmel

tools/perf/util/python.c

@@ -1015,6 +1015,8 @@ PyMODINIT_FUNC initperf(void)
 	    pyrf_cpu_map__setup_types() < 0)
 		return;
 
+	page_size = sysconf(_SC_PAGE_SIZE);
+
 	Py_INCREF(&pyrf_evlist__type);
 	PyModule_AddObject(module, "evlist", (PyObject*)&pyrf_evlist__type);