Use Log::Printf() instead of printf().

llvm-svn: 157869
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
index c5fc4af..fc83724 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -237,7 +237,8 @@
             {
                 if (GetAck () != '+')
                 {
-                    printf("get ack failed...");
+                    if (log)
+                        log->Printf("get ack failed...");
                     return 0;
                 }
             }