Add missing prompt when command doesn't exist (MI)

It fixes the following example:
```
$ bin/lldb-mi --interpreter
(gdb)
-not-found
^error,msg="Driver. Received command '-not-found'. It was not handled. Command 'not-found' not in Command Factory"
-not-found
^error,msg="Driver. Received command '-not-found'. It was not handled. Command 'not-found' not in Command Factory"
```

After the fix it looks like:
```
$ bin/lldb-mi --interpreter
-not-found
^error,msg="Driver. Received command '-not-found'. It was not handled. Command 'not-found' not in Command Factory"
(gdb)
-not-dounf
^error,msg="Driver. Received command '-not-dounf'. It was not handled. Command 'not-dounf' not in Command Factory"
(gdb)
```

llvm-svn: 229131

1 files changed, 1 insertions, 0 deletions

diff --git a/lldb/tools/lldb-mi/MIDriver.cpp b/lldb/tools/lldb-mi/MIDriver.cpp
index 5628e344952..8cd115301ad 100644
--- a/lldb/tools/lldb-mi/MIDriver.cpp
+++ b/lldb/tools/lldb-mi/MIDriver.cpp
@@ -1042,6 +1042,7 @@ CMIDriver::InterpretCommandThisDriver(const CMIUtilString &vTextLine, bool &vwbC
     const CMICmnMIValueResult valueResult("msg", vconst);
     const CMICmnMIResultRecord miResultRecord(cmdData.strMiCmdToken, CMICmnMIResultRecord::eResultClass_Error, valueResult);
     m_rStdOut.WriteMIResponse(miResultRecord.GetString());
+    m_rStdOut.WriteMIResponse("(gdb)");
 
     // Proceed to wait for or execute next command
     return MIstatus::success;