don't use compile-time configuration of libgui as much as possible

We now detect at runtime which sync features to use, which
allows us to remove a lot of the compile-time configuration
options. There  is still one option though, to disable
KHR_fence_sync on some devices (which are more efficient
without it).

- added a backdoor to get the vendor's EGL strings

the new logic is:
- use always ANDROID_native_fence_sync if available
- fallback to KHR_fence_sync if available and not disabled
  by the compile-time option
- use KHR_wait_sync if available and either of the above is
  enabled

Change-Id: I9c4b49d9ff1151faf902cc93bd53ea5f205aaabf
diff --git a/include/private/gui/SyncFeatures.h b/include/private/gui/SyncFeatures.h
new file mode 100644
index 0000000..79fb75b
--- /dev/null
+++ b/include/private/gui/SyncFeatures.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_GUI_SYNC_FEATURES_H
+#define ANDROID_GUI_SYNC_FEATURES_H
+
+#include <utils/Singleton.h>
+#include <utils/String8.h>
+
+
+namespace android {
+// ----------------------------------------------------------------------------
+
+class SyncFeatures : public Singleton<SyncFeatures> {
+    friend class Singleton<SyncFeatures>;
+    bool mHasNativeFenceSync;
+    bool mHasFenceSync;
+    bool mHasWaitSync;
+    String8 mString;
+    SyncFeatures();
+
+public:
+    bool useNativeFenceSync() const;
+    bool useFenceSync() const;
+    bool useWaitSync() const;
+    String8 toString() const;
+};
+
+// ----------------------------------------------------------------------------
+}; // namespace android
+
+#endif // ANDROID_GUI_SYNC_FEATURES_H