The following tests now pass:
glslparsertest/shaders/if1.frag
glslparsertest/shaders/if2.frag
The following tests that used to pass now fail. It appears that most
of these fail because ast_nequal and ast_equal are not converted to HIR.
shaders/glsl-unused-varying.frag
shaders/glsl-fs-sqrt-branch.frag
Add a constructor that uses an ast_struct_specifier and one that uses
a type name. This saves a (trivial) bit of code, but it also ensures
some of the class invariants (i.e., type_name != NULL) are met.
For built-in types, type_name would be NULL. This ensures that
type_name is set even for the built-in types. This simplifies code in
a few places and centralizes the name setting code.
The ast_expression_bin subclass is used for all binary expressions
such as addition, subtraction, and comparisons. Several other
subclasses are soon to follow.
