emulator: opengl: add initLibrary function to render library

This adds an initLibrary() function to libOpenglRender.

It will be used by the emulator to fallback on software rendering
if the library cannot be initialized properly, e.g. if it is not
possible to load the host EGL/GLES libraries.

Change-Id: I41e8ad73a315166e4a15cbee1db72c2552370f46

tools/emulator/opengl/host/libs/libOpenglRender/GL2Dispatch.cpp

@@ -20,6 +20,7 @@
 #include "osDynLibrary.h"
 
 gl2_decoder_context_t s_gl2;
+int                   s_gl2_enabled;
 
 static osUtils::dynLibrary *s_gles2_lib = NULL;
 
@@ -50,6 +51,7 @@ bool init_gl2_dispatch()
     // init the GLES dispatch table
     //
     s_gl2.initDispatchByName( gl2_dispatch_get_proc_func, NULL );
+    s_gl2_enabled = true;
     return true;
 }