The GL versions of get_modelview_matrix, get_projection_matrix and
get_viewport were using glGetDoublev and then converting them to
floats, but it might as well just call glGetFloatv directly.
The GL ES versions were using glGetFixedv but this was being replaced
with glGetFloatv by the #define in the GLES 2 wrappers.
The patch also replaces the glGetFixedv wrapper with
glGetFloatv. Previously this was calling
cogl_gles2_float_array_to_fixed which actually converted to
float. That function has been removed and memcpy is used instead.
