Add TestThreadAPI.py file to house the Python SBThread API test cases.

Currently it has only test cases for SBThread.GetStopDescription() API.

Also modified lldb.swig to add typemap for (char *dst, size_t dst_len)
which occurs for SBThread::GetStopDescription() C++ API.  For Python
scripting:

    # Due to the typemap magic (see lldb.swig), we pass in an (int)length to GetStopDescription
    # and expect to get a Python string as the result object!
    # The 100 is just an arbitrary number specifying the buffer size.
    stop_description = thread.GetStopDescription(100)

llvm-svn: 127173

lldb/test/python_api/thread/main.cpp

@@ -0,0 +1,26 @@
+//===-- main.c --------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include <stdio.h>
+
+// This simple program is to test the lldb Python API related to thread.
+
+char my_char = 'u';
+int my_int = 0;
+
+int main (int argc, char const *argv[])
+{
+    for (int i = 0; i < 3; ++i) {
+        printf("my_char='%c'\n", my_char);
+        ++my_char;
+    }
+
+    printf("after the loop: my_char='%c'\n", my_char); // 'my_char' should print out as 'x'.
+
+    return 0; // Set break point at this line and check variable 'my_char'.
+}