The MB_LEN_MAX macro is the maximum number of bytes needed
to represent a single wide character, in any of the supported locales.
RETURN VALUE
A constant integer greater than zero.
STANDARDS
C11, POSIX.1-2008.
HISTORY
C99, POSIX.1-2001.
NOTES
The entities MB_LEN_MAX and sizeof(wchar_t) are
totally unrelated. In glibc, MB_LEN_MAX is typically 16 (6 in glibc
versions earlier than 2.2), while sizeof(wchar_t) is 4.