Add a bunch more missing ENDs to assembler routines.

This isn't everything; I've missed out those x86 files that are

Change-Id: Idb7bb1a68796d6c0b70ea2b5c3300e49da6c62d2
diff --git a/libc/arch-x86/string/strlen.S b/libc/arch-x86/string/strlen.S
index 4f04ffc..527e36a 100644
--- a/libc/arch-x86/string/strlen.S
+++ b/libc/arch-x86/string/strlen.S
@@ -18,3 +18,4 @@
 	leal	-1(%ecx),%eax		/* and subtracting one */
 	popl	%edi
 	ret
+END(strlen)