Every time we read an empty string we accidentally issue a read for 0
bytes at address 0, this is fine for real memory but the core file
reader doesn't like it.
Fixes an issue reported on the mailing list.
debug_info entries can use DW_AT_abstract_origin to inherit the
attributes of another entry, supporting this attribute is necessary to
support DW_TAG_inlined_subroutine.
Go, starting with 1.10, emits DW_TAG_inlined_subroutine entries when
inlining is enabled.
