Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

- remove non-existent input directories from the configs
- add the target-arch to the project name where applicable (arch dependend code)
- fix comment for __FreeBSD__ [1]

Noticed by: bz [1]

Mechanically add a config for all missing drivers.

No cross-referencing was added to the configs, so no
automatic linking to the documentation of other subsystems.

Drivers which already contain doxygen markup:
agp ath bktr bxe cxgb cxgbe dpt drm e1000 iir
ixgbe mwl nxge ofw pccard siba wpi xen