Use ENTRY and EXIT macros for strcmp, memcpy, atexit.

Without this change strcmp size is zero (not set), and it gets
ignored by Valgrind. Changes to memcpy and atexit don't affect the
generated binary in any way.

Change-Id: I05818cb5951f75901dc8c0eef02807a2e83a9231
diff --git a/libc/arch-arm/bionic/atexit.S b/libc/arch-arm/bionic/atexit.S
index aa1e18d..beea685 100644
--- a/libc/arch-arm/bionic/atexit.S
+++ b/libc/arch-arm/bionic/atexit.S
@@ -37,16 +37,10 @@
 	.eabi_attribute 26, 2
 	.eabi_attribute 30, 4
 	.eabi_attribute 18, 4
-	.code	16
-	.section	.text.atexit,"ax",%progbits
-	.align	2
-	.global	atexit
 	.hidden	atexit
 	.code	16
 	.thumb_func
-	.type	atexit, %function
-atexit:
-	.fnstart
+ENTRY(atexit)
 .LFB0:
 	.save	{r4, lr}
 	push	{r4, lr}
@@ -64,6 +58,5 @@
 .L3:
 	.word	__dso_handle-(.LPIC0+4)
 .LFE0:
-	.fnend
-	.size	atexit, .-atexit
+END(atexit)
 #endif