pru: New validation pass for minrt

pru: New validation pass for minrt

Add a new pru-specific pass to validate that the assumptions for the
minimal C runtime are not violated by the user program.

gcc/ChangeLog:

	* config/pru/pru-passes.cc (class pass_pru_minrt_check): New
	pass.
	(pass_pru_minrt_check::execute): New method.
	(make_pru_minrt_check): New function.
	* config/pru/pru-passes.def (INSERT_PASS_AFTER): Register the
	minrt check pass.
	* config/pru/pru-protos.h (make_pru_minrt_check): Add
	declaration.

gcc/testsuite/ChangeLog:

	* g++.target/pru/minrt-1.cc: New test.
	* g++.target/pru/minrt-2.cc: New test.
	* g++.target/pru/minrt-3.cc: New test.
	* g++.target/pru/pru.exp: New test.
	* gcc.target/pru/minrt-1.c: New test.
	* gcc.target/pru/minrt-2.c: New test.
	* gcc.target/pru/minrt-3.c: New test.

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