Remove special handling of -v in the wrappers.

This was originally introduced to work around some behaviour in the
libtool build, however these days it is actively harmful for a number of
packages, where removing additional arguments when -v is present on the
command line can break ABI detection (notably in CMake packages).

Instead, filter out any references to BUILDLINK_DIR from the libtool
scripts, as that should do the same job.

Retain the ability to run the 'scan' wrapper script, as it can be useful
in certain cases, and is required to support the scan-libtool script
anyway.
Add suport for _WRAP_EXTRA_LIBS.

This allows specifying additional libraries in the output phase, and is
a special case compared to _WRAP_EXTRA_ARGS as we need to ensure that
these libaries are not applied when using Sun ld in -r mode.
Ensure we can use an external libtool for binutils.
Backport fixes from trunk.