[llvm-dwarfdump] Fix misleading scope byte coverage statistics

Fixes PR46575.

Bump statistics version to 6.

Without this patch, for a variable described with a location list the stat
'sum_all_variables(#bytes in parent scope covered by DW_AT_location)' is
calculated by summing all bytes covered by the location ranges in the list and
capping the result to the number of bytes in the parent scope. With the patch,
only bytes which overlap with the parent DIE scope address ranges contribute to
the stat. A new stat 'sum_all_variables(#bytes in any scope covered by
DW_AT_location)' has been added which displays the total bytes covered when
ignoring scopes.