Pointer fixes/improvements.

Allow <, <=, >, >= comparisons of pointers
Allow explicit type-casting of pointers to and from integers
Fix bug in handling expressions of the form "int + ptr" ("ptr + int"
  was fine).
Fix a bug in TypeCastExpr where varying -> uniform typecasts
  would be allowed (leading to a crash later)

opt.cpp

@@ -63,7 +63,7 @@
     #include <llvm/Support/StandardPasses.h>
 #else
     #include <llvm/Transforms/IPO/PassManagerBuilder.h>
-#endif // LLVM_2_8
+#endif // LLVM_2_9
 #include <llvm/ADT/Triple.h>
 #include <llvm/Transforms/Scalar.h>
 #include <llvm/Transforms/IPO.h>