Use ENTRY/END in ARM __get_sp.

Change-Id: If2f159b266f5fa4ad9d188a17d4cd318b605e446
diff --git a/libc/arch-arm/bionic/__get_sp.S b/libc/arch-arm/bionic/__get_sp.S
index 0a313a3..2a7e7b7 100644
--- a/libc/arch-arm/bionic/__get_sp.S
+++ b/libc/arch-arm/bionic/__get_sp.S
@@ -25,10 +25,10 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
-.global __get_sp
-.type __get_sp, %function
 
-__get_sp:
-	mov r0, sp
-	bx lr
+#include <machine/asm.h>
 
+ENTRY(__get_sp)
+  mov r0, sp
+  bx lr
+END(__get_sp)