[PR103074] LRA: Check new conflicts when splitting hard reg live range.

[PR103074] LRA: Check new conflicts when splitting hard reg live range.

Splitting hard register live range can create (artificial)
conflict of the hard register with another pseudo because of simplified
conflict calculation in LRA.  We should check such conflict on the next
assignment sub-pass and spill and reassign the pseudo if necessary.
The patch implements this.

gcc/ChangeLog:

	PR target/103074
	* lra-constraints.cc (split_reg): Set up
	check_and_force_assignment_correctness_p when splitting hard
	register live range.

gcc/testsuite/ChangeLog:

	PR target/103074
	* gcc.target/i386/pr103074.c: New.