Set the shell's unix environment's locale settings to allow for UTF-8 compatibility.

Because the impala-shell now supports printing unicode characters, the user's unix shell needs to allow for UTF-8 compatibility, as there have been cases where the impala-shell has crashed because the user's shell did not support UTF-8.
To resolve this issue, the shell environment's locale setting 'LC_CTYPE' needs to be set to "en_US.UTF-8" unless the user has specifically set this variable already.

A simple export LC_CTYPE=${LC_CTYPE:-en_US.UTF-8} in the shell's environment will suffice, as this doesn't override the user's settings.