Fix compile time errors in --enable-static-modules mode

Fix compile time errors in --enable-static-modules mode

* libpam/pam_static_modules.h (_pam_rhosts_auth_modstruct): Remove
obsolete declaration.
(static_modules): Remove undefined reference to
_pam_rhosts_auth_modstruct.
* modules/pam_pwhistory/opasswd.h: Rename {save,check}_old_password to
{save,check}_old_pass in order to avoid conflicts with pam_unix.
* modules/pam_pwhistory/opasswd.c: Likewise.
* modules/pam_pwhistory/pam_pwhistory.c: Likewise.
* modules/pam_tally2/pam_tally2.c: Rename _pam_tally_modstruct to
_pam_tally2_modstruct.

Signed-off-by: Matveychikov Ilya <i.matveychikov@securitycode.ru>