ggc.h (ggc_free): Declare.

        * ggc.h (ggc_free): Declare.
        * ggc-common.c (ggc_realloc): Use it.
        * ggc-page.c: Remove lots of inline markers.
        (globals): Add free_object_list.
        (ggc_alloc): Tidy.
        (ggc_free, validate_free_objects): New.
        (poison_pages): Provide default.
        (ggc_collect): Call validate_free_objects; emit markers to
        the debug file.

From-SVN: r76801