[C++] include directory configury

[Alex Samuel <samuel at codesourcery dot com>]

This change modifies how the compiled-in path to the G++
target-dependent header files is generated.  The old code produced the
right directory, but in a form which init_standard_includes() did not
match as a subdirectory of cpp_GCC_INCLUDE_DIR.  As a result, if you
moved the G++ installation to another path, the driver couldn't figure
out the location of the target-dependent headers (as it can for, e.g.,
the target-independent G++ headers).

My solution is to use logic for the target-dependent include path
(gcc_gxx_target_include_dir) analogous to what configure generates for
the target-independent include path (gcc_gxx_include_dir) if you don't
specify the --with-gxx-include-dir flag.

This patch is approved by Mark, but it's pretty ugly.  If someone can
suggest a better way of doing this, I'd be happy to provide a more
beautiful patch.

	* Makefile.in (gcc_gxx_target_include_dir): Generate dynamically
	as for gcc_gxx_include_dir.


Index: gcc/Makefile.in
===================================================================
RCS file: /cvs/gcc/egcs/gcc/Makefile.in,v
retrieving revision 1.593
diff -c -p -r1.593 Makefile.in
*** Makefile.in 2001/01/29 01:48:06     1.593
--- Makefile.in 2001/02/02 19:30:40
*************** build_tooldir = $(exec_prefix)/$(target_
*** 319,325 ****
  # Directory in which the compiler finds target-independent g++ includes.
  gcc_gxx_include_dir = @gcc_gxx_include_dir@
  # Directory in which the compiler finds target-dependent g++ includes.
! gcc_gxx_target_include_dir = $(build_tooldir)/include/@libstdcxx_incdir@
  # Directory to search for site-specific includes.
  includedir = $(local_prefix)/include
  # assertdir is overridden in cross-make.
--- 319,325 ----
  # Directory in which the compiler finds target-independent g++ includes.
  gcc_gxx_include_dir = @gcc_gxx_include_dir@
  # Directory in which the compiler finds target-dependent g++ includes.
! gcc_gxx_target_include_dir = $(libsubdir)/$(unlibsubdir)/..`echo $(exec_prefix) | sed -e 's|^$(prefix)||' -e 's|/[^/]*|/..|g'`/$(target)/include/@libstdcxx_incdir@
  # Directory to search for site-specific includes.
  includedir = $(local_prefix)/include
  # assertdir is overridden in cross-make.