Lack of bounds checking in vms-alpha.c parse_module

	PR 29873
	PR 29874
	PR 29875
	PR 29876
	PR 29877
	PR 29878
	PR 29879
	PR 29880
	PR 29881
	PR 29882
	PR 29883
	PR 29884
	PR 29885
	PR 29886
	PR 29887
	PR 29888
	PR 29889
	PR 29890
	PR 29891
	* vms-alpha.c (parse_module): Make length param bfd_size_type.
	Delete length == -1 checks.  Sanity check record_length.
	Sanity check DST__K_MODBEG, DST__K_RTNBEG, DST__K_RTNEND lengths.
	Sanity check DST__K_SOURCE and DST__K_LINE_NUM elements
	before accessing.
	(build_module_list): Pass dst_section size to parse_module.