Add a test case which uses the SBProcess and SBThread APIs to iterate through
the threads and print their stack traces when stopped on a breakpoint.

Add a PrintStackTraces(process) utility function into the lldbutil.py module.

llvm-svn: 115983
diff --git a/lldb/test/threads/main.cpp b/lldb/test/threads/main.cpp
index dddf008..f0af0d1 100644
--- a/lldb/test/threads/main.cpp
+++ b/lldb/test/threads/main.cpp
@@ -65,6 +65,7 @@
         long usec = ::random() % 3000000;
         printf ("%s (thread = %u) doing a usleep (%li)...\n", __FUNCTION__, thread_index, usec);
         ::usleep (usec);
+        printf ("%s (thread = %u) after usleep ...\n", __FUNCTION__, thread_index);
     }
     printf ("%s (thread index = %u) exiting...\n", __FUNCTION__, thread_index);
 
@@ -126,4 +127,4 @@
     err = ::pthread_join (g_thread_3, &thread_result);
 
     return 0;
-}
\ No newline at end of file
+}