* Add support for multiple rtems targets.
- Allow building several specs at one time.
- Support different versions and patches for different targets
  (target-specific specs).

* Improve info files treatment:
- Problem: Infos are not target canonicalized. Therefore, installing them to 
  /usr or /usr/local is likely to conflict with vendor provided infos rsp.
  locally installed packages. Additionally, installing to /usr/local is
  completely out of our control.
- Current approach: Install infos/provide base packages for $prefix!=/usr.
  This is insufficient to solve the problems noted above.
- Consider to install infos/provide base packages only for
  $prefix=/opt/rtems*
- Consider to canonicalize the infos (How?). Probably better be done by
  upstream.

* Strip unnecessary stuff from generated *.specs.

* gcc/build.add: Use --languages=fortran instead of f95 for gcc >= 4.1
  (--languages=f95 is deprecated in gcc >= 4.1)