PR go/47656
	* builtins.def (BUILT_IN_INIT_HEAP_TRAMPOLINE): Define.
	* builtins.c (expand_builtin_init_trampoline): Add onstack
	parameter.  Change caller.
	(expand_builtin): Handle BUILT_IN_INIT_HEAP_TRAMPOLINE.
	* tree.c (build_common_builtin_nodes): Declare
	__builtin_init_heap_trampoline.

From-SVN: r183650