- 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 r290563,r290868,r291038:

r290563:

Integrate tools/regression/lib/libc/net into the FreeBSD test suite
as lib/libc/tests/net

Also, fix eui64_aton_test:test_str(..). The test was comparing the result
of eui64_aton to a pointer of the expected result.

Sponsored by: EMC / Isilon Storage Division

r290868:

Fix -Wformat issues

Reported by: gcc
Sponsored by: EMC / Isilon Storage Division

r291038:

Do not print out errno if the call succeeded unexpectedly; this was a mistake
made in r290868

Reported by: jilles
Sponsored by: EMC / Isilon Storage Division

Integrate tools/regression/lib/libc/net into the FreeBSD test suite
as lib/libc/tests/net

Also, fix eui64_aton_test:test_str(..). The test was comparing the result
of eui64_aton to a pointer of the expected result.

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division

Add regression tests for ethers(3) functions, including new _r variants.
Four tests currently fail:

test_ether_line_bad_1() and test_ether_line_bad_2() due to bugs in
ether_line(3).

test_ether_ntohost() and test_ether_hostton() due to not being fully
implemented tests.