al_have_opengl_extension - Allegro 5 API

       This  function  is a helper to determine whether an OpenGL extension is available on the given display or
       not.

       Example:

              bool packedpixels = al_have_opengl_extension("GL_EXT_packed_pixels");

       If packedpixels is true then you can safely use the constants related to the packed pixels extension.

       Returns true if the extension is available; false otherwise.

Allegro reference manual                                                       al_have_opengl_extension(3alleg5)

       al_have_opengl_extension - Allegro 5 API

              #include <allegro5/allegro_opengl.h>

              bool al_have_opengl_extension(const char *extension)