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/fss.S b/libc/arch-x86/string/fss.S
index 96affab..d819306 100644
--- a/libc/arch-x86/string/fss.S
+++ b/libc/arch-x86/string/fss.S
@@ -15,3 +15,4 @@
 	.align 2
 L1:	xorl	%eax,%eax		/* clear result */
 	ret
+END(ffs)