[DebugInfo][llvm-symbolizer]Add some tests for edge cases when symbolizing

This patch adds half a dozen new tests that test various edge cases in
the behaviour of the symbolizer and DWARF data parsing. All of them test
the current behaviour.

Reviewed by: JDevlieghere, aprantl

Differential Revision: https://reviews.llvm.org/D57741

llvm-svn: 353286