Fix missing pid_t dependency in apparmor.h

The define for pid_t is missing in apparmor.h so that if it is included
in programs that don't also include sys/types.h the compile will break.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <kees.cook@canonical.com>

libraries/libapparmor/src/apparmor.h

@@ -18,6 +18,8 @@
 #ifndef _SYS_APPARMOR_H_
 #define _SYS_APPARMOR_H	1
 
+#include <sys/types.h>
+
 __BEGIN_DECLS
 
 /* Prototypes for apparmor state queries */