arm - Add some comments about the versions of ARM ELF that define various e_flags...

arm - Add some comments about the versions of ARM ELF that define various e_flags values

This patch adds a few comments to include/elf/arm.h to clarify which
versions of the ARM ELF specification defined which headers.  Given
that the EABI is pretty ubiquitous these days, I've marked anything
not based on that as deprecated.

There are no plans to remove any deprecated definitions at this time,
but any new development shouldn't be building upon support for
deprecated definitions remaining in the long term.

	* elf/arm.h: Updated comments for e_flags definitions.