Fixed DataExtractor to correctly display Intel extended doubles.

This means that "register read stmm0 --format f" actually works now.

This is a little messy but LLDB assumes 'long double' is portable, when it is not.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@188698 91177308-0d34-0410-b5e6-96231b3b80d8