make bootstrap failure for 971105

[Jeffrey A Law]

  In message < 9711181757.AA74366@earth.hekimian.com >you write:
  > The following occurs while making an AIX 3.2.5 cross-compiler under
  > hpux 10.10.
  > 
  > I had previously modified libgcc2.c to hard-code the path for stdio.h,
  > because of a similar error.  (The very thought of trying to figure out
  > what to set on the "make" line to get the right -I in the right place
  > threatens my mental health so I avoided that.  :-))
This is a generic cross compilation issue -- to build libgcc2 you must have
include files for the target in a place where the compiler can/will find
them.

jeff