_mesa_glsl_parse_state should be the parent for all temporary allocation
done while compiling a shader. glsl_shader should only be used as the
parent for the shader's final IR---the _result_ of compilation.
Since many IR instructions may be added or discarded during optimization
passes, IR should not ever be allocated to glsl_shader directly.
Done via sed -i s/talloc_parent(state)/state/g and s/talloc_parent(st)/st/g.
This also removes a ton of talloc_parent calls, which may help performance.
Now that all scalar, vector, and matrix constructors are emitted
in-line, the parameters to these constructors should not be flattened
to a pile of scalars. Instead, the functions that emit the in-line
constructor bodies can directly write the parameters to the correct
locations in the objects being constructed.