Log message:
Add t-crtstuff to tmake_file on NetBSD amd64.

Log message:
Add the lang/gcc47/buildlink3.mk file

Log message:
Import gcc-4.7.0 and lang/gcc47

GCC 4.7.0 is a major release, containing substantial new
functionality not available in GCC 4.6.x or previous GCC releases.

GCC 4.7 features support for software transactional memory on
selected architectures.  The C++ compiler supports a bigger
subset of the new ISO C++11 standard such as support for atomics
and the C++11 memory model, non-static data member initializers,
user-defined literals, alias-declarations, delegating constructors,
explicit override and extended friend syntax.  The C compiler adds support
for more features from the new ISO C11 standard.  GCC now supports
version 3.1 of the OpenMP specification for C, C++ and Fortran.

The link-time optimization (LTO) framework has seen improvements
with regards to scalability, stability and resource needs.  Inlining
and interprocedural constant propagation have been improved.

GCC 4.7 now supports various new GNU extensions to the DWARF debugging
information format, like entry value and call site information, a typed
DWARF stack and a more compact macro representation.

Extending the widest support for hardware architectures in the
industry, GCC 4.7 gains support for Adapteva's Epiphany processor,
National Semiconductor's CR16, and TI's C6X as well as Tilera's
TILE-Gx and TILEPro families of processors.  The x86
family support has been extended by the Intel Haswell and AMD Piledriver
architectures.  ARM has gained support for the Cortex-A7 family.

See

  http://gcc.gnu.org/gcc-4.7/changes.html

for more information about changes in GCC 4.7.