- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

MFp4: Increase character timeout to 10. Make it a #define for easier
changes in the future. This helps with getting started and to
overcome the really sucky level of granuality this timeout has in
getc. A timeout of 1 means 'wait until top of next second' rather
than 'wait for at least a second'.

MFp4 (checkpoint of work in progress):

o Use a directory layout that is more akin to the i386 boot layout.
o Create a libat91 for library routines that are used by one or more
of the boot loaders.
o Create bootiic for booting from an iic part.
o Create bootspi for booting from an spi part.
o Optimize the size of many of these routines (especially emac.c). Except
for the emac.c optimizations, all these have been tested.
o eliminate the inc directory, libat91 superceeds it.
o Move linker.cfg up a layer to allow it to be shared.