- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

Fix the problem that surfaced with the new binutils import on sparc64
(and that is for now being worked around by a binutils patch).

The rtld code tested &_DYNAMIC against 0 to see whether rtld itself
was built as PIC or not. While the sparc64 MD code did not rely
on the preset value of the GOT slot for _DYNAMIC any more due
to previous binutils changes, it still used to not be 0, so
that this check did work. The new binutils do however initialize
this slot with 0. As a consequence, rtld would not properly initialize
itself and crash.
Fix that by introducing a new macro, RTLD_IS_DYNAMIC, to take the role
of this test. For sparc64, it is implemented using the rtld_dynamic()
code that was already there. If an architecture does not provide its
own implementation, we default to the old check.

While being there, mark _DYNAMIC as a weak symbol in the sparc64
rtld_start.S. This is needed in the LDSCRIPT case, which is however
not currently supported for want of an actual ldscript.

Sanity checked with md5 on alpha, amd64, i386 and ia64.

Avoid using the global offset table to get the address of _DYNAMIC in
rtld. When _DYNAMIC is referenced normally from C the global offset
table is used implicitly, but newer versions of binutils don't initialize
it statically in the binary, so this doesn't work until rtld is relocated,
which _DYNAMIC is needed for... So, as on other systems with the same
problem, we disassemble a call instruction to _DYNAMIC in order to get
its address.

Allow threading libraries to register their own locking
implementation in case default one provided by rtld is
not suitable.

Consolidate various identical MD lock implementation into
a single file using appropriate machine/atomic.h.

Approved by: re (scottl)

Fix the handling of high PLT entries (> 32764) on sparc64. This requires
additional arguments to reloc_jmpslot(), which is why MI code and MD code
of other platforms had to be changed.

Reviewed by: jake
Approved by: re

Add END markers to asm functions so that debuggers can find their size.

rtld support for sparc64.

Largely obtained from: netbsd
Submitted by: jake, tmm