add libsurfaceflinger_ddmconnection for PDK build

- the library is dlopened from libsurfaceflinger
- the library built only when libnativehelper exists

Bug: 7089510
Change-Id: Ib3ea1029d7e8f6e055f4b759d0bf68f5123fa8a1
diff --git a/services/surfaceflinger/DdmConnection.cpp b/services/surfaceflinger/DdmConnection.cpp
index 433b38e..ece965c 100644
--- a/services/surfaceflinger/DdmConnection.cpp
+++ b/services/surfaceflinger/DdmConnection.cpp
@@ -23,6 +23,10 @@
 
 namespace android {
 
+void DdmConnection_start(const char* name) {
+    ALOGI("DdmConnection_start");
+    DdmConnection::start(name);
+}
 
 void DdmConnection::start(const char* name) {
     JavaVM* vm;