pru: Refactor to use passes definition file

pru: Refactor to use passes definition file

Switch to using a passes definition file instead of explicitly
registering the PRU-specific passes in pru.cc.  This would make it
cleaner to add new PRU-specific passes.

There are no functional changes.

gcc/ChangeLog:

	* config/pru/pru-passes.cc (class pass_tiabi_check): Rename to
	add "pru_" prefix.
	(class pass_pru_tiabi_check): Ditto.
	(pass_tiabi_check::execute): Ditto.
	(pass_pru_tiabi_check::execute): Ditto.
	(make_pru_tiabi_check): Ditto.
	(pru_register_abicheck_pass): Remove.
	* config/pru/pru-protos.h (pru_register_abicheck_pass): Remove.
	(make_pru_tiabi_check): Add declaration.
	* config/pru/pru.cc (pru_option_override): Remove explicit pass
	registration.
	* config/pru/t-pru: Register PRU passes definition file.
	* config/pru/pru-passes.def: New file.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>