Patch by Ari Grant

"Open LLDB and run:
(lldb) script print lldb.debugger.GetInputFileHandle()

This puts the debugger into a catatonic state and all interactions seem
to enter a black hole. The reason is that executing this commnand
actually *CLOSES* the input file handle and so all input is dropped on
the floor. Oof!

The fix is simple: flush a descriptor, instead of closing it, when
transferring ownership."

llvm-svn: 198835