- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r280959:
Correctly handle __fcntl_compat symbol for the !SYSCALL_COMPAT case.

Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).

MFC r276630:
Remove interposing, fix malloc, reinstall signal handlers wrappers on
libthr load.

MFC r276681:
Avoid calling internal libc function through PLT or accessing data
though GOT.

MFC r277032:
Reduce the size of the interposing table and amount of
cancellation-handling code in the libthr.

MFC note:
r276646 ("do not erronously export 'openat' symbol from rtld") is not
applicable to stable/10 yet, since PATHFDS support was not merged.

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

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

(Incomplete) fixes for symbols visibility issues and style in fcntl.h.

Append '__' prefix to the tag of struct oflock, and put it under BSD
namespace. Structure is needed both by libc and kernel, thus cannot be
hidden under #ifdef _KERNEL.

Move a set of non-standard F_* and O_* constants into BSD namespace.
SUSv4 explicitely allows implemenation to pollute F_* and O_* names
after fcntl.h is included, but it costs us nothing to adhere
to the specification if exact POSIX compliance level is requested by
user code.

Change some spaces after #define to tabs.

Noted by and discussed with: bde
MFC after: 1 week

Call the fcntl compatiblity wrapper from the thread library fcntl wrappers
so that they get the benefit of the (limited) forward ABI compatibility.

MFC after: 1 week

Make fcntl() a weak symbol so that it can be overridden by thread libraries.

MFC after: 2 days

Add some compatibility code so that software which is built to use the new
struct flock with l_sysid member can work properly on an an old kernel which
doesn't support l_sysid.

Sponsored by: Isilon Systems