* params.def (ggc-min-expand, ggc-min-heapsize): New parameters.
	* doc/invoke.texi: Document them.

	* ggc-page.c: Include params.h.  Remove definitions of
	GGC_MIN_EXPAND_FOR_GC, GGC_MIN_LAST_ALLOCATED.  Replace
	GGC_POISON with ENABLE_GC_CHECKING in ifdefs, delete #define.
	(init_gcc): Don't set G.allocated_last_gc here.
	(ggc_collect): Use PARAM_VALUE (GGC_MIN_HEAPSIZE) and
	PARAM_VALUE (GGC_MIN_EXPAND) to decide whether or not to
	perform collection.
	* ggc-simple.c: Similarly.
	* Makefile.in (ggc-common.o, ggc-simple.o): Add $(PARAMS_H) to
	dependencies.

From-SVN: r59034