Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC: r231620, r237098

Enable TLS support for ARM toolchain

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Now that TLS is supported for sparc64 by both binutils 2.17.50 committed
in r218822 and rtld(1) committed in r219533 turn on TLS support in GCC.

Add FreeBSD/MIPS support to GCC.

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.