+rcDestroySyncKHR, don't leak on swapBuffers

This CL is part of this host CL to clean up EGL sync objects:

https://android-review.googlesource.com/#/c/267892/

It does the following:
- adds rcDestroySyncKHR
- avoids creating an actual EGL sync object when in swapBuffers(),
  because it will be cumbersome to delete it from the guest.
  Instead, it specifically calls rcCreateSyncKHR and tells the host
  to clean up the object when it has become signaled.
- refactors rcCreateSyncKHR / goldfish_sync_queue_work to
  a common function.
- bumps the GLAsyncSwap version string to "ANDROID_EMU_native_sync_v2",
  so that the emulator can work with all combinations of
  old/new emulator/system-image.

Change-Id: Iff9a5e226b4026b955893c6f4d6ff3266009da6b
diff --git a/system/renderControl_enc/renderControl_client_context.cpp b/system/renderControl_enc/renderControl_client_context.cpp
index 8fb6588..a41a7e9 100644
--- a/system/renderControl_enc/renderControl_client_context.cpp
+++ b/system/renderControl_enc/renderControl_client_context.cpp
@@ -47,6 +47,7 @@
 	rcFlushWindowColorBufferAsync = (rcFlushWindowColorBufferAsync_client_proc_t) getProc("rcFlushWindowColorBufferAsync", userData);
 	rcCreateClientImagePuid = (rcCreateClientImagePuid_client_proc_t) getProc("rcCreateClientImagePuid", userData);
 	rcDestroyClientImagePuid = (rcDestroyClientImagePuid_client_proc_t) getProc("rcDestroyClientImagePuid", userData);
+	rcDestroySyncKHR = (rcDestroySyncKHR_client_proc_t) getProc("rcDestroySyncKHR", userData);
 	return 0;
 }