Fixed an issue where the LLDB command prompt isn't interactive if you use -o -O -S -s or specify a file on the command line.

This means TAB completion wasn't working and editline wasn't being used.

<rdar://problem/17872824> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@214428 91177308-0d34-0410-b5e6-96231b3b80d8