[lldb] Return all line entries matchign a line if no column is specified

Previously, if no column was specified, ResolveSymbolContext would take
the first match returned by FindLineEntryIndexByFileIndex, and reuse it
to find subsequent exact matches. With the introduction of columns, columns
are now considered when matching the line entries.

This leads to a problem if one wants to get all existing line entries
that match that line, since now the column is also used for the exact match.
This way, all line entries are filtered out that have a different
column number, but the same line number.

This patch changes that by ignoring the column information of the first match
if the original request of ResolveSymbolContext was also ignoring it.

Reviewed By: mib

Differential Revision: https://reviews.llvm.org/D108816