d: Defer compiling inline definitions until after the module has finished.

d: Defer compiling inline definitions until after the module has finished.

This is to prevent the case of when generating the methods of a struct
type, we don't accidentally emit an inline function that references it,
as the outer struct itself would still be incomplete.

gcc/d/ChangeLog:

	* d-tree.h (d_defer_declaration): Declare.
	* decl.cc (function_needs_inline_definition_p): Defer checking
	DECL_UNINLINABLE and DECL_DECLARED_INLINE_P.
	(maybe_build_decl_tree): Call d_defer_declaration instead of
	build_decl_tree.
	* modules.cc (deferred_inline_declarations): New variable.
	(build_module_tree): Set deferred_inline_declarations and a handle
	declarations pushed to it.
	(d_defer_declaration): New function.