Problem rolling GMP and MPFR into a GCC build

[Justin Seyster <jrseys@xxxxxxxxx>]

I ran into a problem trying to build the 4.5.0 GCC release with GMP
and MPFR placed directly in the source directory.  During the GCC
build process, GMP compiles fine, but MPFR fails with the error
message:

checking for recent GMP... yes
checking for gmp internal files... configure: error: header files
gmp-impl.h and longlong.h not found

I put the most recent MPFR (3.0.0) in an "mpfr" directory and the most
recent GMP (5.0.1) in a "gmp" directory, both in the main GCC source
directory.  This same technique worked for previous GCC 4.5 snapshots,
but it isn't working now for the release itself (which I checkout from
SVN by its tag).  This is all on an up-to-date Karmic machine.  (Also,
I am using a separate build directory.)

Any ideas what might have gone wrong?  Thanks!
        --Justin