glsl: Add image built-in function generator.
Because of the combinatorial explosion of different image built-ins
with different image dimensionalities and base data types, enumerating
all the 242 possibilities would be annoying and a waste of .text
space. Instead use a special path in the built-in builder that loops
over all the known image types.
v2: Generate built-ins on GLSL version 4.20 too. Rename
'_has_float_data_type' to '_supports_float_data_type'. Avoid
duplicating enumeration of image built-ins in create_intrinsics()
and create_builtins().
v3: Use a more orthodox approach for passing image built-in generator
parameters.
v4: Cosmetic changes.
Acked-by: Paul Berry <stereotype441@gmail.com>