Make the gcc-14 toolchain track the development tips of gcc, binutils, and glibc to support loop vectorization

[thixotropist]

Issue #6 requires generation and analysis of RISCV-64 binaries compiled with loop auto-vectorization. That capability is expected mid 2024 - and will likely fluctuate significantly between now and then. Components to this toolchain include:

• binutils source repo tracking https://sourceware.org/git/binutils-gdb.git
• gcc source repo tracking git://gcc.gnu.org/git/gcc.git
• glibc source repo tracking git@github.com:bminor/glibc.git
• three build directories based on the above, configured for a 64 bit linux-capable RISCV processor
• a bootstrap sysroot directory copied from https://github.com/riscv/riscv-gnu-toolchain and updated with binaries exported from the above
• local patches needed for hermetic Bazel builds
• the Bazel build system, release 7.0 or better

[thixotropist]

completed - but not documented - with commit ad0f7133cfa813606b03a14afae2318c2ecf7844