Basic varying struct test
varying-struct-arrays
varying-struct-copy
varying-struct-interpolation
varying-struct-centroid
shader_runner regression with gles

Augment the parser that examines the shader_test file passed in
with the test to determine which brand of shader_running to
execute, shader_runner, shader_runner_gles2, etc.

This fixes a bug where GLSL ES if first in the [required] section
could match against GL after which the wrong shader_runner command
would be used due to the wrong gl api being used.

Last if plain GLSL is found, GL is presumed as the api. If GLSL ES
is found, GL ES is presumed as the api.

When dispatch is implemented for GLES all this can go away.

Signed-off-by: Tom Gall <tom.gall@linaro.org>