Improve location for new statements in match-and-simplify phiopt

Before match-and-simplify was used in phiot, the location of the
new stamtents were all of that of the conditional, this adds that
back as I did not realize gimple_simplify didn't do that for you.

OK? Bootstrapped and tested on x86_64 with no regressions.

gcc/ChangeLog:

	* tree-ssa-phiopt.c (gimple_simplify_phiopt): Annotate the
	new sequence with the location of the conditional statement.