New function split_block

[Jeffrey A Law]

  In message < 14781.56110.137969.172959@paradise.net.nz >you write:
  > 
  > This patch provides a new function to split a basic block at a given
  > insn.  It creates a new fallthru edge between the blocks and returns
  > the new edge.  This function is used in a forthcoming loop patch that
  > adds fake edges to the CFG after each call insn that may exit.
  > 
  > Michael.
  > 
  > 
  > 2000-09-12  Michael Hayes  <mhayes@cygnus.com>
  > 
  > 	* basic-block.h (split_block, update_bb_for_insn): New prototypes.
  > 	* flow.c (split_block, update_bb_for_insn): New functions.
Approved.  Please install.

Thanks,
jeff