I like home brew, but would it be possible to get around issues with dependencies by simply providing statically linked binaries?
I used to build all the the pre-requisites (at least on OS X) separately with only static libraries which yielded the result you're describing. I see that I'm now sucking in some dynamic library dependencies because the homebrew ports provide both static and dynamic libs.
I should be able to update those dependency builds (still in the Makefile, but probably broken) and at least provide that as an unsupported option and a way to properly make the binaries static.
GCC comes with a script (contrib/download_prerequisites) that downloads the gmp/mpc/mpfr sources into the GCC sourcetree. The GCC build process then builds the libraries automatically as part of its normal build process.