Unified multiple definitions of container_of() macro.

Removed duplicate definitions of the container_of() macro and
refactored sources to use the single implementation.

Signed-off-by: Jon A. Cruz <jonc@osg.samsung.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
diff --git a/src/pixman-renderer.c b/src/pixman-renderer.c
index 23315b1..b19875d 100644
--- a/src/pixman-renderer.c
+++ b/src/pixman-renderer.c
@@ -32,6 +32,7 @@
 #include <assert.h>
 
 #include "pixman-renderer.h"
+#include "shared/helpers.h"
 
 #include <linux/input.h>