It isn't necessary to buffer the last character of strings. This can cause a
bug with strings that have 1 character between 0x0041 and 0x01b0.
[BZ #13691]
* iconvdata/tcvn5712-1.c (FROM_LOOP): Fix a bug when converting strings
with only 1 character between 0x0041 and 0x01b0.
* wcsmbs/Makefile (tests): Add tst-mbsnrtowcs.
* wcsmbs/tst-mbsnrtowcs.c: New file.