* basic_block.h: Added prototype for reorder_basic_blocks.
        * toplev.c: Changes to add -freorder-blocks and graph dump after
        block reordering is done.
        * flow.c (reorder_block_def): New structure for use during block
        reordering.
        (REORDER_BLOCK_*): New macros to access members of above structure.
        (skip_insns_between_block, get_common_dest, chain_reorder_blocks,
        make_reorder_chain, fixup_reorder_chain, reorder_basic_blocks): New
        functions for block reordering.

Co-Authored-By: Jason Eckhardt <jle@cygnus.com>

From-SVN: r31968