Fix strcpy.c that should have been strcpy.S. DO NOT MERGE

Merge from internal master.

(cherry-picked from 1ce665416307628f4bcaced86faa64bdf9c489c3)

Change-Id: I376b831df42248baadde7202a30a68112f752ff7
diff --git a/libc/arch-arm/generic/generic.mk b/libc/arch-arm/generic/generic.mk
index 0b3f644..c3a5aa5 100644
--- a/libc/arch-arm/generic/generic.mk
+++ b/libc/arch-arm/generic/generic.mk
@@ -2,5 +2,5 @@
 $(call libc-add-cpu-variant-src,MEMSET,arch-arm/generic/bionic/memset.S)
 $(call libc-add-cpu-variant-src,STRCAT,string/strcat.c)
 $(call libc-add-cpu-variant-src,STRCMP,arch-arm/generic/bionic/strcmp.S)
-$(call libc-add-cpu-variant-src,STRCPY,arch-arm/generic/bionic/strcpy.c)
+$(call libc-add-cpu-variant-src,STRCPY,arch-arm/generic/bionic/strcpy.S)
 $(call libc-add-cpu-variant-src,STRLEN,arch-arm/generic/bionic/strlen.c)