glib/tests/date.c: Fix the tests on non-English Windows

The names of the month (and abbreviations) are specific to the Windows
system locale, so we need to use SetThreadLocale() to set the locale of
the running program to en-US so that it will parse "March" and "Sept" etc.
correctly.

https://bugzilla.gnome.org/show_bug.cgi?id=719344
glib/tests/keyfile.c: Use g_close()

Use g_close() instead, as close() is really found in io.h on Windows, not
unistd.h as on Unix, and hence unistd.h is not universally available.

https://bugzilla.gnome.org/show_bug.cgi?id=719344