lz4: add memmove to arm string.c

armsrc/string.c

@@ -20,6 +20,23 @@ void *memcpy(void *dest, const void *src, int len) {
     return dest;
 }
 
+void *memmove (void *dest, const void *src, size_t len)
+{
+  char *d = dest;
+  const char *s = src;
+  if (d < s)
+    while (len--)
+      *d++ = *s++;
+  else
+    {
+      char *lasts = (char*)s + (len-1);
+      char *lastd = d + (len-1);
+      while (len--)
+        *lastd-- = *lasts--;
+    }
+  return dest;
+}
+
 void *memset(void *dest, int c, int len) {
     uint8_t *d = dest;
     while ((len--) > 0) {