[DWARF parser] DWARFDebugFrame: Make FrameEntry struct smaller.

FrameEntry doesn't need to hold a reference to the section it is
located in. Instead, pass DataExtractor as an argument of parsing
function.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207461 91177308-0d34-0410-b5e6-96231b3b80d8