PR c++/83058 - ICE on C++ code with negative array index: in warn_placement_new_too_small

gcc/cp/ChangeLog:

	PR c++/83058
	* init.c (warn_placement_new_too_small): Use offset_int instead of
	HOST_WIDE_INT.

gcc/testsuite/ChangeLog:

	PR c++/83058
	* g++.dg/warn/Wplacement-new-size-5.C: New test.

From-SVN: r255182