This function returns the total number of bytes that make up the multibyte
character, not the number of bytes that were needed to complete the multibyte
character, on some platforms:
-HP-UX 11.11, Solaris 10.
+HP-UX 11.11, Solaris 11 2010-11.
@item
This function may not return 0 when parsing the NUL character on some platforms:
Solaris 9.