GitLab

* Makefile now uses shared HAL makefile fragment
* Filenames converted to consistent OS-agnostic forms
* Remove PIC attributes from AREA declarations: since the code isn't
  position-independent, this is factually incorrect, and will produce
  false linker warnings when we link with libraries that are also non-PIC
* Replaced a couple of UAL instructions with their pre-UAL counterparts to
  reduce number of warnings
* Remove unused header file
* Remove --cpu overrride from ASFLAGS (since objasm 4.12, --cpu Cortex-A9 no
  longer warns about SMI)

Note, now requires objasm 4.12 to build (due to hdr suffixes in filespecs).