[RFC] Use accessor macros for the head and end of a basic block

[law@redhat.com]

In message <20031208220915.GA32401@atrey.karlin.mff.cuni.cz>, Jan Hubicka write
s:
 >> Opinions? Should I finish this patch or is this just a big no-no?
 >
 >I think it is right thing to do.  How will the tree counterparts called?
 >Perhaps we can use BLOCK_HEAD_RTL/BLOCK_HEAD_TREE to make naming more
 >conventient.
I would _strongly_ recommend this go into the mainline first, otherwise
we're going to create a lot of gratutious changes which makes merging
(both to the branch and eventually to the mainline) a lot more work than
it ought to be.
jeff