add support for GL_EXT_debug_marker

This extension is always added to the GL_EXTENSIONS
extension string for the current GL context, regardless
of if it's supported by the h/w driver.

The extension itself will be handled by GLES_trace (eventually),
when GLES_trace is not enabled, it'll result to a no-op.

If the h/w implementation has this extension, we'll call that version
instead of our dummy version.

Change-Id: Ie5dd3387c4d45cd5ed5f03b73bda6045620a96bc
diff --git a/opengl/libs/EGL/egl_object.h b/opengl/libs/EGL/egl_object.h
index 7106fa5..abd4cbb 100644
--- a/opengl/libs/EGL/egl_object.h
+++ b/opengl/libs/EGL/egl_object.h
@@ -28,6 +28,7 @@
 #include <GLES/glext.h>
 
 #include <utils/threads.h>
+#include <utils/String8.h>
 
 #include <system/window.h>
 
@@ -158,11 +159,11 @@
     typedef egl_object_t::LocalRef<egl_context_t, EGLContext> Ref;
 
     egl_context_t(EGLDisplay dpy, EGLContext context, EGLConfig config,
-            int impl, egl_connection_t const* cnx, int version) :
-        egl_object_t(get_display(dpy)), dpy(dpy), context(context),
-                config(config), read(0), draw(0), impl(impl), cnx(cnx),
-                version(version) {
-    }
+            int impl, egl_connection_t const* cnx, int version);
+
+    void onLooseCurrent();
+    void onMakeCurrent(EGLSurface draw, EGLSurface read);
+
     EGLDisplay dpy;
     EGLContext context;
     EGLConfig config;
@@ -171,6 +172,7 @@
     int impl;
     egl_connection_t const* cnx;
     int version;
+    String8 gl_extensions;
 };
 
 class egl_image_t: public egl_object_t {