Make tritex test run with latest OpenGL driver.

Use EGLUtils::selectConfigForNativeWindow to select a legitimate
configuration. (Before now we had been selecting an incorrect
configuration, but the older drivers let us get away with it.)

Converted the source to C++ so we can call selectConfigForNativeWindow.
diff --git a/opengl/tests/tritex/Android.mk b/opengl/tests/tritex/Android.mk
index 76fd8dd..6db3f49 100644
--- a/opengl/tests/tritex/Android.mk
+++ b/opengl/tests/tritex/Android.mk
@@ -2,7 +2,7 @@
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES:= \
-	tritex.c
+	tritex.cpp
 
 LOCAL_SHARED_LIBRARIES := \
 	libcutils \