libgcc rpaths with --enable-version-specific-runtime-libs

[IainS <developer at sandoe-acoustics dot co dot uk>]

when libgcc multilibs are built the Makefile forces two vars to be  
empty during the build phase viz:

	  slibdir= libsubdir= MULTIOSDIR=$(MULTIDIR)

unfortunately, "libsubdir" is used in configure.ac like this.

AC_ARG_WITH(slibdir,
[  --with-slibdir=DIR      shared libraries in DIR [LIBDIR]],
slibdir="$with_slibdir",
if test "${version_specific_libs}" = yes; then
  slibdir='$(libsubdir)'
elif test -n "$with_cross_host" && test x"$with_cross_host" != x"no";  
then
  slibdir='$(exec_prefix)/$(host_noncanonical)/lib'
else
  slibdir='$(libdir)'
fi)
AC_SUBST(slibdir)

and slibdir :
shlib_slibdir = @slibdir@

and shlib_slibdir ends up as the path for the instal_name (via  
shlib_slibdir expansion in the LINK fragment).

== the upshot is that (at least on dawin) when building with "-- 
enable-version-specific-runtime-libs"

libgcc gets built with

/libgcc_s.1.dylib

as the embedded rpath

This then gets referenced by the other libs (e.g. libgfortran.dylib)  
[ because the stub libs 10.X refer to it].

Whilst the libgcc path is corrected in the install phase; the  
references in the other libraries are not.

====

libsubdir is expanded
libsubdir = $(libdir)/gcc/$(host_noncanonical)/$(version)

in Makefile.in.

If this expansion is applied in configure.ac,  all works OK on darwin.
i.e.
if test "${version_specific_libs}" = yes; then
  slibdir='$(libdir)/gcc/$(host_noncanonical)/$(version)'

Would that change cause a problem on any other target?

Iain