This patch adds the ability to create a gsym::LineTable object, populate it, encode and decode it and test all functionality.
The full format of the LineTable encoding is specified in the header file LineTable.h.
Differential Revision: https://reviews.llvm.org/D66602
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371657 91177308-0d34-0410-b5e6-96231b3b80d8
