Fix setting of locale
OpenBSD, for example, doesn't have a locale named "UTF8", as illustrated
here:
/usr/share/locale $ ls
ARMSCII-8 CP866 ISO8859-13 ISO8859-2 ISO8859-5 ISO8859-9 KOI8-U
CP1251 ISO8859-1 ISO8859-15 ISO8859-4 ISO8859-7 KOI8-R UTF-8
This causes UTF-8 characters to not be displayed, despite the LC_CTYPE
environment variable being set to "en_US.UTF-8" (which corresponds to an
actual locale on the system).
To avoid this issue, instead of telling getlocale(3) to use a fixed
locale, tell it to use the system's locale. From `man 3 setlocale`:
Only three locales are defined by default, the empty string "" which
denotes the native environment, and the "C" and "POSIX" locales, which
denote the C language environment.
