Allow native BSD build of libg++ 2.7.1. This is a complete replacement of

Allow native BSD build of libg++ 2.7.1.  This is a complete replacement of
the GNU build procedure, not a wrapper.  Generates standard, profiled,
shared object, and shared library versions of libiberty, libstdc++, and
libg++.  libiberty version 0.0, libstdc++ version 27.1, and libg++ version
27.1.  Requires modification of bsd.subdir.mk pmake include.  Targets
linked with the shared libraries libstdc++ and libg++ will, by default,
automatically be run time linked with libm and libcurses.