r14659: Fix installpammodules for shells where a

r14659: Fix installpammodules for shells where a

   for module in ; do ... ; done

leads to an error (true64, solaris 8).

We now use {,UN}INSTALL_PAM_MODULES to get replaced by configure.
Therfore we don't run into the {,un}installpammodules rule if no PAM
module is requested.

Thanks to Björn Jacke for pointing to this issue.
(This used to be commit 07a70f8f861235ba4037aacb9cc835b6d18f51c3)