Changed rendering to remove need for sampler names.

Changed rendering to remove need for sampler names.

Used glGetActiveUniform to introspect the shader and get the sampler
uniforms. No longer need to store the sampler names with the textures.

The program now generates a list of active texture sampler locations;
The renderer has been changed to bind textures using the matching sampler index.

Affects test cases that check GL state for particular sampler names, as these
are no longer queried.

Change-Id: I194570eb3ec35160a18ee0aebb6f978805855b1a
Signed-off-by: David Steele <david.steele@samsung.com>