[ale] Where does 'makedepend' find its default libs?

[jmills at siberia.gtri.gatech.edu (John M. Mills)]

Apologies -- this is really a gcc question, but it came up from my
Slackware installation, so I toss it out here.

I updated my gcc from 2.5.8 to 2.6.3, removing, then installing with
the respective Slackware pkgtool scripts.  When I run makedepend, it
looks for the i486-linux 'includes' in:
  /usr/src/gcc-2.5.8/lib/gcc-lib/i486-linux/2.5.8/include

Of course it doesn't find them.  The files are actually in:
  /usr/lib/gcc-lib/i486-linux/2.6.3/include

I have added this -I to CFLAGS in my makefile, but it seems a very clumsy and
unportable solution.  How can I tell 'makedepend' once and for-all where to
look for the compiler-dependent includes?  Similarly, where does 'gcc' look
to know where its includes should be sought.  I have seen references to a
file containing this information, but I can't find any references to it
now.  I actually suspect some obsolete definition file lying around, but I
haven't been able to identify it.

TIA --jmm--

John M. Mills, Senior Research Engineer   --   john.m.mills at gtri.gatech.edu
   Georgia Tech Research Institute, Georgia Tech, Atlanta, GA 30332-0853
        Phone contacts: 770.528.3258 (voice), 770.528.7083 (FAX)
        EMACS: 'Eight Megabytes And Constantly Swapping' -- anon