[complib:mpfr] Fix building MPFR in some weird cases

The tmul test uses a compiled-in input file in $(srcdir).
The problem is that the Makefile passes it unquoted. The C code
tries to stringify it using clever macros, which may *usually* work.

In my case the source directory was named:
.../toolchain-powerpc-e500v2-linux-gnuspe-1.0-2.fc10/.../tests
And guess what? During testing I found out the program fails because
it tries to open:
.../toolchain-powerpc-e500v2-1-gnuspe-1.0-2.fc10/.../tests

Yes, CPP tokenized the macro before stringifying it and not surprisingly
the 'linux' part was converted to 1.
[on Fedora-10: cpp (GCC) 4.3.2 20081105 (Red Hat 4.3.2-7)]

So the attached patch simplify the macros and pass the path as string
from the Makefile.

Manually backported from 1449:8ad2773e7ae3

 # This file declares functions for bare metal kernel (IE. none)

 # Copyright 2008 Yann E. MORIN

 # Licensed under the GPL v2. See COPYING in the root of this package

 CT_DoKernelTupleValues() {

     # For bare-metal, there is no kernel part in the tuple

     CT_TARGET_KERNEL=

 }

 do_kernel_get() {

     :

 }

 do_kernel_extract() {

     :

 }

 do_kernel_headers() {

     :

 }