Add stpcpy assembler version.

For generic, continue to use the C version of the code.

Bug: 13746695
Change-Id: I77426a70b06131f2373bb51265bea1240bb3f101
diff --git a/libc/arch-arm/generic/generic.mk b/libc/arch-arm/generic/generic.mk
index 2456e6e..95be867 100644
--- a/libc/arch-arm/generic/generic.mk
+++ b/libc/arch-arm/generic/generic.mk
@@ -7,4 +7,5 @@
     bionic/memmove.c \
     bionic/__strcat_chk.cpp \
     bionic/__strcpy_chk.cpp \
+    upstream-openbsd/lib/libc/string/stpcpy.c \
     upstream-openbsd/lib/libc/string/strcat.c \