sb: Do not create a build set tar file on error.

If creating build set tar files and using --keep-going do not create
the tar file if any part of the set build fails.
sb: Do no install with a Cxc build.
rtems: Revert gdb to gdb-7.6 as gdb-7.6.1 fails.
sb: Add include/lib paths for /usr/pkg to NetBSD.
doc: Add NetBSD.
config: Use ${build_top} to change dir to parent.

On NetBSD with ksh changing into a symlink made PWD the link's
target path so a 'cd ..' returned you to that parent and not
the parent you started from. Record the build top and then
change back to that path.

Change the package names to the actual packages and remove the
extra directory in the build tree. This makes the paths simpler.
rtems: Newlib version CVS 15-Sept-2013
Search any path for CVS on Darwin (MacOS).
Split FLAGS into CFLAGS and LDFLAGS.

The clang compiler on MacOS 10.9 (Maverick) generated a warning when
LDFLAGS where passed on the command line. This change lets the RSB
build RTEMS GCC tools on a clean Maverick install.