[lldb] Make GetDIENamesAndRanges() allow 0-valued decl and call lines

In an upcoming patch, D142556, Clang is proposed to be changed to emit
line locations that are inlined at line 0. This clashed with the behavior of
GetDIENamesAndRanges() which used 0 as a default value to determine if
file, line or column numbers had been set. Users of that function then
checked for any non-0 values when setting up the call site:

  if (call_file != 0 || call_line != 0 || call_column != 0)
    [...]

which did not work with the Clang change since all three values then
could be 0.

This changes the function to use std::optional to catch non-set values
instead.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D142552