Added 64-bit POSIX support to write general-purpose floating-point registers.
- Includes tests that write, verify and restore floating-point register content using SBFrame.

Reviewed by: Daniel Malea


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@180111 91177308-0d34-0410-b5e6-96231b3b80d8