audit: inline audit_syscall_entry to reduce burden on archs

Every arch calls:

if (unlikely(current->audit_context))
	audit_syscall_entry()

which requires knowledge about audit (the existance of audit_context) in
the arch code.  Just do it all in static inline in audit.h so that arch's
can remain blissfully ignorant.

Signed-off-by: Eric Paris <eparis@redhat.com>

kernel/auditsc.c

@@ -1632,7 +1632,7 @@ void audit_free(struct task_struct *tsk)
  * will only be written if another part of the kernel requests that it
  * be written).
  */
-void audit_syscall_entry(int arch, int major,
+void __audit_syscall_entry(int arch, int major,
 			 unsigned long a1, unsigned long a2,
 			 unsigned long a3, unsigned long a4)
 {