Arm32 dynamic function dispatch

Previous change was reverted in 9690b121e342676453c58f5940964350762085a0.
This change added .arch directive to kryo/ to avoid invalid instruction error.

Test: Run bionic unit test.
Test: Use gdb to make sure the right function is selected.
Test: Build previously failed target: make PRODUCT-sdk_phone_arm64-sdk
Change-Id: I14de41851121fc1a0b38c98fda5eb844b6a9695c
diff --git a/libc/arch-arm/generic/bionic/strcpy.S b/libc/arch-arm/generic/bionic/strcpy.S
index c0ab9e5..89bd699 100644
--- a/libc/arch-arm/generic/bionic/strcpy.S
+++ b/libc/arch-arm/generic/bionic/strcpy.S
@@ -33,7 +33,11 @@
 
 .syntax unified
 
-ENTRY(strcpy)
+// To avoid warning about deprecated instructions, add an explicit
+// arch. The code generated is exactly the same.
+.arch armv7-a
+
+ENTRY(strcpy_generic)
 	pld	[r1, #0]
 	eor	r2, r0, r1
 	mov	ip, r0
@@ -131,4 +135,4 @@
 	cmp	r2, #0
 	bne	4b
 	bx	lr
-END(strcpy)
+END(strcpy_generic)