dwarf: add dwarf v4 maximum_operations_per_instruction to DWARFDebugLine.

See http://reviews.llvm.org/D5533 for details.

Change by Tong Shen.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@218641 91177308-0d34-0410-b5e6-96231b3b80d8