in general, SOLARIS should use /usr/bin/ld.

Make equivalent to unxgcc.mk (with gld).
NB: use $(READELF) updated in configure.ac and config_host.mk.in

Signed-off-by: Michael Stahl <mstahl@redhat.com>
(cherry picked from commit d6afd367167ed406cd97192da358b776dbf5158e)

Conflicts:
	solenv/gbuild/platform/solaris.mk

note: while cherry-picking to master, removed all mention of toolchains
that are unsupported on master due to lack of C++11 support (GCC < 4.6).

Change-Id: Iaf175fb7db095c567e9837eac8456c0c3809e334
Reviewed-on: https://gerrit.libreoffice.org/12384
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>