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>

llvm-svn: 207816