denver: optimize memmove

Optimize 32-bit denver memmove with reversal memcpy.

Change-Id: Iaad0a9475248cdd7e4f50d58bea9db1b767abc88
diff --git a/libc/arch-arm/generic/generic.mk b/libc/arch-arm/generic/generic.mk
index 2bc84e0..2456e6e 100644
--- a/libc/arch-arm/generic/generic.mk
+++ b/libc/arch-arm/generic/generic.mk
@@ -4,6 +4,7 @@
     arch-arm/generic/bionic/strcmp.S \
     arch-arm/generic/bionic/strcpy.S \
     arch-arm/generic/bionic/strlen.c \
+    bionic/memmove.c \
     bionic/__strcat_chk.cpp \
     bionic/__strcpy_chk.cpp \
     upstream-openbsd/lib/libc/string/strcat.c \