- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r260401

Remove aicasm as a build dependency. It made sense when the ahc and ahd
drivers and their firmware were under active development, but those days
have passed. The firmware now exists in pre-compiled form, no longer
dependent on it's sources or on aicasm. If you wish to rebuild the
firmware from source, the glue still exists under the 'make firmware'
target in sys/modules/aic7xxx.

This also fixes the problem introduced with r257777 et al with building
kernels the old fashioned way in sys/$arch/compile/$CONFIG when the
ahc/ahd drivers were included.

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

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

Disable -Wconstant-conversion warnings for the aic7xxx module in a more
fine-grained way: only add the option for the specific .c files that
need them, like via sys/conf/files.

MFC after: 1 week

Amend r228779 by also disabling -Wconstant-conversion warnings for the
aic7xxx module.

MFC after: 1 week

Allow the ahc and ahd drivers to be built as modules. This also
breaks the ahc driver into a core back-end and pci and eisa
front-ends.