[LLVM-478] Clang and GCC code size comparison - Looked at CMSIS-DSP, clang consistently produces smaller code than GCC in contrast to Zephyr. Recorded some specific areas - Tidied up scripts and build system patches to post for review - Wrote up a readme for how to reproduce the results

[Misc] - LLD reviews for reducing image-size using some VA/PA address alignment tricks. - MC and LLD changes to add MOV[WNZ] relocations. - Looked into why our container might be giving Resource unavailable during ninja check-all

Some thoughts on ABI process.