Addresses #293

Checkpoint in lock tree implementation.
Write locks and point locks appear to be done,
bugs fixed in comparison function.

Need to do a bunch of worst case error handling still.

git-svn-id: file:///svn/tokudb@1830 c7de825b-a66e-492c-adef-691d508d4ae1

src/lock_tree/locktree.h

@@ -23,8 +23,8 @@ typedef struct {
 } toku_lock_tree;
 #warning TODO: Handle 'panicked' variable in every api call.
 
-extern DBT* toku_lt_infinity;
-extern DBT* toku_lt_neg_infinity;
+extern const DBT* toku_lt_infinity;
+extern const DBT* toku_lt_neg_infinity;
 
 const unsigned __toku_default_buflen = 2;
 /*