Environment helper functions use random naming ('env' prefix or suffix or
both, with or without '_'). Change to POSIX naming scheme ('env' suffix,
no '_').
Env_setenv has more in common with putenv than setenv. Change to do_putenv.
Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Stepan Kasal <kasal@ucw.cz> Signed-off-by: Junio C Hamano <gitster@pobox.com>