Make gensyscalls.py use the ALIAS_SYMBOL macro.

Change-Id: Ib94c0abb6fc85126ecc5ed3f1962b2b8b90b9952
diff --git a/libc/arch-arm/syscalls/fstatat64.S b/libc/arch-arm/syscalls/fstatat64.S
index ce56c36..03e0052 100644
--- a/libc/arch-arm/syscalls/fstatat64.S
+++ b/libc/arch-arm/syscalls/fstatat64.S
@@ -13,5 +13,4 @@
     b       __set_errno_internal
 END(fstatat64)
 
-    .globl fstatat
-    .equ fstatat, fstatat64
+ALIAS_SYMBOL(fstatat, fstatat64)