Add support for the ELF flags
Move target/hexagon/cpu.[ch] to be v73
Change the compiler flag used by "make check-tcg"

The decbin instruction is removed in Hexagon v73, so check the
version before trying to compile the instruction.

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230427224057.3766963-2-tsimpson@quicinc.com>