gdb/dwarf: change read_loclist_index complaints into errors

gdb/dwarf: change read_loclist_index complaints into errors

Unlike read_rnglists_index, read_loclist_index uses complaints when it
detects an inconsistency (a DW_FORM_loclistx value without a
.debug_loclists section or an offset outside of the section).  I really
think they should be errors, since there's no point in continuing if
this situation happens, we will likely segfault or read garbage.

gdb/ChangeLog:

	* dwarf2/read.c (read_loclist_index): Change complaints into
	errors.

Change-Id: Ic3a1cf6e682d47cb6e739dd76fd7ca5be2637e10