fix [2187212] add support for GLESv2 dispatch based on TLS

Instead of using a different function pointer table for ES 1.x and ES 2.x,
we use a single one that is the union (sort|uniq) of both tables. Two
instances of this table are initialized with pointers to GL ES 1.x and GL ES 2.x
entry-points.
When a context is created, we store its version number and when it is bound to a
thread we set the approruiate table based on the stored version.

This introduce no penalty while dispatching gl calls to the right API version.

[Pending Dr No approval for MR1]
diff --git a/opengl/libs/egl_impl.h b/opengl/libs/egl_impl.h
index ac286cb..1fba209 100644
--- a/opengl/libs/egl_impl.h
+++ b/opengl/libs/egl_impl.h
@@ -23,18 +23,19 @@
 #include <EGL/eglext.h>
 #include <EGL/eglplatform.h>
 
+#include "hooks.h"
+
 // ----------------------------------------------------------------------------
 namespace android {
 // ----------------------------------------------------------------------------
 
-struct gl_hooks_t;
-
 struct egl_connection_t
 {
     void *              dso;
-    gl_hooks_t *        hooks;
+    gl_hooks_t *        hooks[2];
     EGLint              major;
     EGLint              minor;
+    egl_t               egl;
 };
 
 EGLAPI EGLImageKHR egl_get_image_for_current_context(EGLImageKHR image);