This is a cherry-pick of Matúš's e2f30c078fcf26d481c2e90398b450f6c475a483
from the feature/gbuild branch, with the following modifications by
Stephan Bergmann <sbergman@redhat.com>:
* Adapt salhelper/Makefile to what all those Makefiles currently need to
look like.
* Do not remove salhelper/source/gcc3.map, instead add directly into it
what otherwise solenv/bin/addsym.awk would add to it on Linux.
* In salhelper/Library_salhelper.mk, add code that on Linux takes care of
the soname and symbol versioning required for backwards compatibility.
Solaris would need those features too, and its backwards compatibility
is thus currently broken. Also add a bad hack to create the soname
symlink (xxx.3 -> xxx) in the solver needed on non-Windows platforms (it
is a bad hack for now in that it e.g. is not removed by "make clean").
* In solenv/gbuild/platform/macosx.mk, add an even worse hack to set the
correct install name for libuno_salhelpergcc3.dylib.3, with a trailing
".3".
* also change GNUMakefile.mk to find the RepositoryModule_*.mk, instead of Module_*.mk
* subsequenttests was broken by the introduction of tail_build, because there where two Module_*.mk in root
