gstgldisplay: use of GL_DEPTH_COMPONENT16 if OpenGL ES 2.0
gstgldisplay: use of GL_DEPTH_COMPONENT16 if OpenGL ES 2.0

glRenderbufferStorage does not accept GL_DEPTH_COMPONENT in
OpenGL ES 2.0.

Fix bug #593786

ystreet/gst-plugins-gl,ystreet/gst-plugins-gl,mapmapteam/gst-plugins-gl,mapmapteam/gst-plugins-gl,mapmapteam/gst-plugins-gl,ystreet/gst-plugins-gl