binutils stabs type list

binutils stabs type list

Fuzzers have found that specifying a large stab type number results in
lots of memory being requested, as the list is extended with a 16
element array at a time until we reach the given stab type.  It also
takes a long time.  Of course normal sane stab types use small
positive integers, but it's not hard to modify the code to handle type
numbers starting anyhere.

	* stabs.c (struct stab_types): Add base_index.
	(stab_find_slot): Simplify filenum check.  Delete type number
	check.  Don't allocate entire array from 0 to type number,
	allocate a sparse array.