By default, the start_ip_offset in libunwind's table_entry struct is
relative to the unw_dyn_info_t's segbase. This presents a problem
for us in conjunction with using LLVM's MCJIT because it likes to
spread text sections and the corresponding eh_frame sections quite
far apart. This represents my attempt to support this use case in the
simplest manner that is backwards compatible, by adding a new format
kind (UNW_INFO_FORMAT_REMOTE_TABLE2) that indicates that the
`start_ip_offset` should be interpreted as relative to `start_ip`
rather than segbase.
(_U_dyn_op_label_state): Drop "qp" and "when" arguments.
(_U_dyn_op_copy_state): Ditto.
(_U_dyn_op_stop): Define qp to _U_QP_TRUE and when to -1.
(_U_QP_TRUE): New macro.
(Logical change 1.56)
(unw_dyn_info_format_t): New type.
(unw_dyn_op): Decrease "tag" from 16 to 8 bits, ditto for "qp" member.
(unw_dyn_proc_info): Change "name" pointer to "name_ptr" value (unw_word_t) and
make padding explicit.
(unw_dyn_table_info): Change "name" pointer to "name_ptr" value. Rename
"table_size" to "table_len" and change type of table_data from
void * to "unw_word_t *".
(unw_dyn_info): Switch to doubly-linked list so _U_dyn_cancel() can be O(1).
Change type of "format" member from enum to int32_t. Make padding explicit.
(unw_dyn_info_list): Make "generation" member 32 bits wide. Add "version" member
to enable future extensions to the dynamic info list.
(_U_dyn_register): Don't return anything (it can't fail).
(_U_dyn_cancel): Ditto.
(Logical change 1.30)
