4.8.1 fails to build on x86_64-unknown-linux-gnu

[Piotr Wyderski <piotr dot wyderski at gmail dot com>]

I have a set of the required libraries built and installed into
separate directories, so when gcc is configured with:

../configure --prefix=/opt/tools/gcc-4.8.1
--with-gmp=/opt/tools/gmp-5.1.2 --with-mpfr=/opt/tools/mpfr-3.2.1
--with-mpc=/opt/tools/mfr=/opt/tools/mpfr-3.2.1
--with-mpc=/opt/tools/mpc-1.0.1 --with-ppl=/opt/tools/ppl-1.1
--with-cloog=/opt/tools/cloog-0.18.0 --enable-languages=c,c++
--disable-multilib

during configure-stage1-target-libgcc:

configure: error: cannot compute suffix of object files: cannot compile

and config.log contains:

configure:3565: checking for suffix of object files
configure:3587: /mnt/local/piotrw/build/gcc-4.8.1/objdir/./gcc/xgcc
-B/mnt/local/piotrw/build/gcc-4.8.1/objdir/./gcc/
-B/opt/tools/gcc-4.8.1/x86_64-unknown-linux-gnu/bin/
-B/opt/tools/gcc-4.8.1/x86_64-unknown-linux-gnu/lib/ -isystem
/opt/tools/gcc-4.8.1/x86_64-unknown-linux-gnu/include -isystem
/opt/tools/gcc-4.8.1/x86_64-unknown-linux-gnu/sys-include    -c -g -O2
 conftest.c >&5
/mnt/local/piotrw/build/gcc-4.8.1/objdir/./gcc/cc1: error while
loading shared libraries: libmpc.so.3: cannot open shared object file:
No such file or directory
configure:3591: $? = 1
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "GNU C Runtime Library"
| #define PACKAGE_TARNAME "libgcc"
| #define PACKAGE_VERSION "1.0"
| #define PACKAGE_STRING "GNU C Runtime Library 1.0"
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL "http://www.gnu.org/software/libgcc/";
| /* end confdefs.h.  */
|
| int
| main ()
| {
|
|   ;
|   return 0;
| }
configure:3605: error: in
`/mnt/local/piotrw/build/gcc-4.8.1/objdir/x86_64-unknown-linux-gnu/libgcc':
configure:3608: error: cannot compute suffix of object files: cannot compile
See `config.log' for more details.

which indicates that the configure scripts somehow failed to add the
mpc libpath to the command line.

Best regards, Piotr