audit: support the "standard" <asm-generic/unistd.h>

Many of the syscalls mentioned in the audit code are not present
for architectures that implement only the "standard" set of
Linux syscalls (e.g. openat, but not open, etc.).  This change
adds proper #ifdefs for all those syscalls.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/lib/audit.c b/lib/audit.c
index 8e7dc1c..76bbed4a 100644
--- a/lib/audit.c
+++ b/lib/audit.c
@@ -36,8 +36,10 @@
 int audit_classify_syscall(int abi, unsigned syscall)
 {
 	switch(syscall) {
+#ifdef __NR_open
 	case __NR_open:
 		return 2;
+#endif
 #ifdef __NR_openat
 	case __NR_openat:
 		return 3;