Improve backwards compatibility with GNU Make

libc/str/tprecode8to16.c

@@ -46,6 +46,9 @@ static inline noasan axdx_t tprecode8to16_sse2(char16_t *dst, size_t dstsize,
 /**
  * Transcodes UTF-8 to UTF-16.
  *
+ * This is a low-level function intended for the core runtime. Use
+ * utf8toutf16() for a much better API that uses malloc().
+ *
  * @param dst is output buffer
  * @param dstsize is shorts in dst
  * @param src is NUL-terminated UTF-8 input string