EGL: default to swap interval 1

This change explicitly sets swap interval 1 on the window when an
EGLSurface is created to render to it.

Change-Id: I91eb29dbee3ae4a55076b921f084d503fbe94e03
diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index 0561909..1aa0e2d 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -1005,6 +1005,11 @@
     return mCurrentScalingMode;
 }
 
+bool SurfaceTexture::isSynchronousMode() const {
+    Mutex::Autolock lock(mMutex);
+    return mSynchronousMode;
+}
+
 int SurfaceTexture::query(int what, int* outValue)
 {
     Mutex::Autolock lock(mMutex);