- 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 r282067:

Integrate tools/regression/fifo into the FreeBSD test suite as tests/sys/fifo
and tools/regression/file into the FreeBSD test suite as tests/sys/file

Integrate tools/regression/fifo into the FreeBSD test suite as tests/sys/fifo
and tools/regression/file into the FreeBSD test suite as tests/sys/file

MFC after: 1 week

Integrate tools/regression/file into the FreeBSD test suite as tests/sys/file

Integrate more tests into the FreeBSD test suite from tools/regression, etc

When extending a file with truncate, check that newly added bytes have
a value of 0 in the extended region.

Make sure that we get EINVAL back if we try to truncate a read-only
file descriptor.

Add regression tests to make sure that attempting to call ftruncate() on
various non-file objects fails.

Add very basic ftruncate() regression test, with a comment rather more
thorough than the tests regarding what should be tested.