I haven't been able to get the linux compiler in linux-build-gcc-4.8.x to build either under most circumstances. I've found that with both the commands in linux.mk and the PKGBUILD files on Arch Linux, it builds when --prefix=/usr is specified in configure, but not when any other prefix is specified. I've tried messing around with --with-sysroot=, --with-headers=, and --disable-bootstrap, but they all cause various errors at different points in the build process.
With the default configure options, it determines that /lib/cpp is how the C preprocessor should be run when building libiberty.a and fails. I applied a patch for vxworks mkdir in libgcov that comes with the Arch Linux PKGBUILD, which got it past that but caused compiler errors while building libstdc++:
Code:
/tmp/gcc-test-build/build/powerpc-wrs-vxworks/libstdc++-v3/include/bits/atomic_base.h:228:62: error: invalid type in declaration before ';' token
typedef __atomic_base<uintmax_t> atomic_uintmax_t;
I got the windows side of the toolchain working though with the Wix Toolset, after I tweaked Toolchain.wxs and windows.mk. I'll submit a pull request for it and some bug fixes for bugs in the todo list later today.