- 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 r294900:

Implement AT_SECURE properly.

AT_SECURE auxv entry has been added to the Linux 2.5 kernel to pass a
boolean flag indicating whether secure mode should be enabled. 1 means
that the program has changes its credentials during the execution.
Being exported AT_SECURE used by glibc issetugid() call.

Submitted by: imp, dchagin
Security: FreeBSD-SA-16:10.linux
Security: CVE-2016-1883

MFC r293613:

Implement vsyscall hack. Prior to 2.13 glibc uses vsyscall
instead of vdso. An upcoming linux_base-c6 needs it.

MFC r289055 (by mjg@):

linux: fix handling of out-of-bounds syscall attempts

Due to an off by one the code would read an entry past the table, as
opposed to the last entry which contains the nosys handler.

This fixes my fault.

MFC r289058 (by cem@):

Fix missing semi-colon from r289055.

MFC r289768 (by jhb@):

Merge r289055 to amd64/linux32:

linux: fix handling of out-of-bounds syscall attempts

Due to an off by one the code would read an entry past the table, as
opposed to the last entry which contains the nosys handler.

MFC r283474:

Rework signal code to allow using it by other modules, like linprocfs:

1. Linux sigset always 64 bit on all platforms. In order to move Linux
sigset code to the linux_common module define it as 64 bit int. Move
Linux sigset manipulation routines to the MI path.

2. Move Linux signal number definitions to the MI path. In general, they
are the same on all platforms except for a few signals.

3. Map Linux RT signals to the FreeBSD RT signals and hide signal conversion
tables to avoid conversion errors.

4. Emulate Linux SIGPWR signal via FreeBSD SIGRTMIN signal which is outside
of allowed on Linux signal numbers.

PR: 197216

MFC r283467:

Call nosys in case when the incorrect syscall number is specified.

Its my fault, fixed by mjg@ at r289055.

MFC r283431:

Add AT_RANDOM and AT_EXECFN auxiliary vector entries which are used by
glibc. At list since glibc version 2.16 using AT_RANDOM is mandatory.

MFC r283424:

Add preliminary support for x86-64 Linux binaries.

Add preliminary support for x86-64 Linux binaries.

Differential Revision: https://reviews.freebsd.org/D1076