glsl2: Use _mesa_glsl_parse_state as the talloc parent, not glsl_shader.

_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.

src/glsl/hir_field_selection.cpp

@@ -33,7 +33,7 @@ _mesa_ast_field_selection_to_hir(const ast_expression *expr,
 				 exec_list *instructions,
 				 struct _mesa_glsl_parse_state *state)
 {
-   void *ctx = talloc_parent(state);
+   void *ctx = state;
    ir_rvalue *result = NULL;
    ir_rvalue *op;