aarch64: fix old_mmap output for arm personality

* mem.c (SYS_FUNC(old_mmap)) [AARCH64]: Fetch mmap arguments
as 32-bit integers.
diff --git a/mem.c b/mem.c
index dbca9a6..2ca8954 100644
--- a/mem.c
+++ b/mem.c
@@ -94,8 +94,8 @@
 SYS_FUNC(old_mmap)
 {
 	long u_arg[6];
-# if defined(X86_64)
-	/* We are here only in personality 1 (i386) */
+# if defined AARCH64 || defined X86_64
+	/* We are here only in a 32-bit personality. */
 	int i;
 	unsigned narrow_arg[6];
 	if (umoven(tcp, tcp->u_arg[0], sizeof(narrow_arg), narrow_arg) == -1)