- 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

Add compiler support for the ARM EABI.

ARM EABI support is disabled by default and can be enabled by setting
WITH_ARM_EABI when building, however only the kernel-toolchain target will
work with this flag until the rest of the support is added.

Add strndup(3) prototype to string.h.

This change was erronously ommitted from the r185690, and attempt
to simply add the prototype to string.h has revealed that several
contributed programs defined local prototypes for strndup(), controlled
by autoconfed config.h. So, manually change #undef HAVE_STRNDUP to
#define HAVE_STRNDUP 1. Next import of the corresponding program would
regenerate config.h, overriding the changes in this commit.

No objections from: kan

Update bmake glue to build GCC 4.2.

Also:
Switch FreeBSD to use libgcc_s.so.1.

Use dl_iterate_phdr to locate shared objects' exception frame
info instead of depending on older register_frame_info machinery.
This allows us to avoid depending on libgcc_s.so.1 in binaries
that do not use exception handling directly. As an additional
benefit it breaks circular libc <=> libgcc_s.so.1 dependency too.

Build newly added libgomp.so.1 library, the runtime support
bits for OpenMP.

Build LGPLed libssp library. Our libc provides our own
BSD-licensed SSP callbacks implementation, so this library
is only built to benefit applications that have hadcoded
knowledge of libssp.so and libssp_nonshared.a. When linked
in from command line, these libraries override libc
implementation.