- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r275660: Fix the watchdog timeout calculation to prevent wrap.

MFC r256871, r259034, r266010

r256871:
Implement watchdog function and register it with watchdog list.

r259034:
Make the sysctl node read-only.

r266010:
Remove extra newlines.
No functional changes.

MFC r261410

Follow r261352 by updating all drivers which are children of simplebus
to check the status property in their probe routines.

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

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

Add barebone Raspberry Pi port. Supported parts:
- Interrupts controller
- Watchdog
- System timer
- Framebuffer (hardcoded resolution/bpp)