On NetBSD 7.0, m4 tests fail because they use nonexistent uselocale

[Roland Illig]

Building m4 ends with this:

test-localename.c: In function 'test_locale_name':
test-localename.c:74:3: warning: implicit declaration of function
'uselocale' [-Wimplicit-function-declaration]
   uselocale (LC_GLOBAL_LOCALE);
   ^

And later an undefined reference to uselocale.

The code already contains #ifdefs for HAVE_NEWLOCALE, but that seems to
be different from HAVE_USELOCALE, which also exists.

Roland