Fixed CTRL+C related issues:
- CTRL+C wasn't clearing the command in lldb
- CTRL+C doesn't work in python macros in lldb
- Ctrl+C no longer interrupts the running process that you attach to

<rdar://problem/15949205> 
<rdar://problem/16778652> 
<rdar://problem/16774411>



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@207816 91177308-0d34-0410-b5e6-96231b3b80d8