Remove an unused variable from pam_unix.

This variable was added in r82352 back in 2001, but even then it didn't
have any use. Because it's not marked static, the C compiler won't
complain about it.

Discussed with:	des

lib/libpam/modules/pam_unix/pam_unix.c

@@ -81,8 +81,6 @@ static char password_hash[] =		PASSWORD_HASH;
 #define PAM_OPT_LOCAL_PASS	"local_pass"
 #define PAM_OPT_NIS_PASS	"nis_pass"
 
-char *tempname = NULL;
-
 /*
  * authentication management
  */