set LANG=C in environment

Without this patch, initdb would not work for me.

<pre>
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) initdb: encoding mismatch
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) The encoding you selected (UTF8) and the encoding that the
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) selected locale uses (LATIN1) do not match.  This would lead to
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) misbehavior in various character string processing functions.
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) Rerun initdb and either do not specify an encoding explicitly,
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) or choose a matching combination.
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) The files belonging to this database system will be owned by user "postgres".
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) This user must also own the server process.
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) The database cluster will be initialized with locales
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   COLLATE:  C
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   CTYPE:    en_US
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   MESSAGES: C
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   MONETARY: en_US
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   NUMERIC:  en_US
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns)   TIME:     C
/usr/bin/initdb --encoding 'UTF8' --pgdata '/var/lib/pgsql/data' returned 1 instead of one of [0]
(/Stage[main]/Postgresql::Initdb/Exec[postgresql_initdb]/returns) change from notrun to 0 failed: /usr/bin/initdb --encoding 'UTF8' --pgdata '/var/lib/pgsql/data' returned 1 instead of one of [0]
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