GitLab

Deploys both a native binary to RiscOS/Library and a cross-compiling one
to the GitLab runner machine.

Fix issues identified by CI:
* Several header files were missing copyright notices and licence terms:
  copy these from the corresponding source files.
* Tell GitLab that one source file is yacc format (rouge syntax colour
  library doesn't know yacc, so select C as next-best fit).

Requires RiscOS/Sources/Lib/OSLib!2
!NoTag