Re: Fix an undefined behaviour in the BFD library's DWARF parser

Using an unsigned int cast (to 32 bits) on a pointer difference (of
possibly 64 bits) is wrong.  Even though it will work on all real
object files, the fuzzers will eventually find this hole.

	PR 28687
	* dwarf1.c (parse_die): Cast pointer difference to size_t.
	Catch another possible pointer overflow.