[llvm-debuginfo-analyzer] Fix memory leak reported by sanitizers.

The sanitizer reported memory leak issues; the command line
used in the test case is:

llvm-debuginfo-analyzer --attribute=level
                        --print=instructions
                        pr-incorrect-instructions-dwarf-clang.o

When dealing with logical instruction lines associated with
an artificial logical scope, skip the process of finding
their enclosing scope. Just add them to the scope.

Create logical debug lines only if the command line specifies:
  --print=lines or --print=elements or --print=all

Reviewed By: jryans, vitalybuka

Differential Revision: https://reviews.llvm.org/D137156