bootstrap: Replace GNU toolchain seeds with Mes for i686-linux.

* gnu/packages/bootstrap.scm (%bootstrap-inputs)[i686-linux]: Replace
%bootstrap-gcc, %bootstrap-binutils, %bootstrap-glibc with %mescc-tools-seed,
%mes-seed, %srfi-43 and %tinycc-seed.
* gnu/packages/make-bootstrap.scm (%bootstrap-tarballs)[i686-linux]: Replace
gcc-tarball, binutils-tarball, glibc-tarball with %mescc-tools-seed,
%mes-seed, %srfi-43 and %tinycc-seed.
* gnu/packages/commencement.scm (%bootstrap-inputs+toolchain)[i686-linux]: Add
glibc-mesboot, binutils-mesboot, gcc-wrapper, gcc-mesboot.
(file-boot0)[i686-linux]: Disable strip-binaries?, validate-runpath?.
(libstdc++-boot0)[i686-linux]: Add libtool install workarourd: copy
libstdc++.so.0.0.20 from gcc-mesboot.
(gcc-boot0)[i686-linux]: Add libtool install workaround: touch
libcc1.so.0.0.0, libcc1plugin.so.0.0.0.
(perl-boot0): Disable validate-runpath?.
(bison-boot0)[i686-linux]: Do not use ranlib -D.