Set __bionic_asm_align to 16 for arm64

As for others targets, it is better to align function text by minimim
cacheline size.  This patch changes arm __bionic_asm_align to 16.

Test: bionic tests on aarch64.
Change-Id: Ib121663c65493d33d6803e2c5139d247a8cae858
diff --git a/libc/private/bionic_asm_arm64.h b/libc/private/bionic_asm_arm64.h
index 43ecaf3..463ca31 100644
--- a/libc/private/bionic_asm_arm64.h
+++ b/libc/private/bionic_asm_arm64.h
@@ -37,7 +37,7 @@
 
 #pragma once
 
-#define __bionic_asm_align 0
+#define __bionic_asm_align 16
 
 #undef __bionic_asm_function_type
 #define __bionic_asm_function_type %function