Add language option in -gdb-show command (MI)

Summary:
Add language option in -gdb-show command + test:
```
$ bin/lldb-mi ~/p/hello
[...]
b main
[...]
r
[...]
(gdb)
-gdb-show language
^done,value="c++"
(gdb)
quit
```

Test Plan: ./dotest.py -v --executable $BUILDDIR/bin/lldb tools/lldb-mi/

Reviewers: abidh, granata.enrico, jingham, clayborg

Reviewed By: clayborg

Subscribers: lldb-commits, jingham, granata.enrico, clayborg, abidh

Differential Revision: http://reviews.llvm.org/D9279

llvm-svn: 235983

lldb/scripts/interface/SBLanguageRuntime.i

@@ -0,0 +1,22 @@
+//===-- SWIG Interface for SBLanguageRuntime --------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+namespace lldb {
+
+class SBLanguageRuntime
+{
+public:
+    static lldb::LanguageType
+    GetLanguageTypeFromString (const char *string);
+    
+    static const char *
+    GetNameForLanguageType (lldb::LanguageType language);
+};
+
+} // namespace lldb