- 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 r276187, r276190, r271422:

Rename pmap_kenter_temp to pmap_kenter_temporary to be consistent with the
other architectures with this function.

Eliminate unnecessary references to pte.h internals by using the standard
pmap_kenter_temporary() to map pages while dumping.

Cleanup up ARM *frame structures.

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

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

Final whitespace trim.

Return Supervisor SP and LR registers instead of User ones while in KDB thread.

Obtained from: Semihalf

Fix gdb_cpu_getreg() to actually match GDB's register
definition.

Add remote GDB bits for arm.