Silence "assignment discards ‘const’ qualifier from pointer target type" warnings.

Silence "assignment discards ‘const’ qualifier from pointer target type" warnings.

* gettext-tools/src/msginit.c (language_team_address): New local variable
'result'.
(plural_forms): Adjust type of local variable 'dirs'.
* gettext-tools/src/xg-message.c (remember_a_message): Reduce scope and adjust
type of local variable 'msgstr'.
(remember_a_message_plural): New local variable 'msgstr1_malloc'.
* gettext-tools/src/xgettext.c (main): New local variable
'defaulted_output_dir'.