Don't memmove the buffer content unless it's needed

src/dbuf.c

@@ -50,7 +50,10 @@ uc_dbuf_ensure(DBuf *buf, size_t capacity)
         return 0;
     len = uc_dbuf_len(buf);
     sz = buf->start - buf->bufstart;
+
+    if (buf->bufstart != buf->start)
         memmove(buf->bufstart, buf->start, len);
+
     if (sz + remaining < capacity) {
         size_t newlen = uc_dbuf_buflen(buf) + capacity;
         void *tmp = realloc(buf->bufstart, newlen);
@@ -75,6 +78,7 @@ uc_dbuf_trim(DBuf *buf)
     if (len == 0)
         return;
 
+    if (buf->bufstart != buf->start)
         memmove(buf->bufstart, buf->start, len);
 
     tmp = realloc(buf->bufstart, len);