tree-into-ssa.c (mark_def_sites_global_data): Make KILLS bitmap a sparse bitmap instead of a simple bitmap.

        * tree-into-ssa.c (mark_def_sites_global_data): Make KILLS
        bitmap a sparse bitmap instead of a simple bitmap.
        (mark_def_sites_initialize_block):  Corresponding changes.
        (ssa_mark_def_sites_initialize_block): Likewise.
        (ssa_mark_phi_uses): Likewise.
        (mark_def_site, ssa_mark_def_sites): Likewise.
        (mark_def_site_blocks): Likewise.
        (rewrite_ssa_into_ssa): Likewise.

From-SVN: r94519