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)

run_tests.py

@@ -107,7 +107,7 @@ def run_tasks_from_queue(queue):
         # is this a test to make sure an error is issued?
         want_error = (filename.find("tests_errors") != -1)
         if want_error == True:
-            ispc_cmd = "ispc --nowrap --woff %s --arch=%s --target=%s" % \
+            ispc_cmd = "ispc --nowrap %s --arch=%s --target=%s" % \
                 ( filename, options.arch, options.target)
             sp = subprocess.Popen(shlex.split(ispc_cmd), stdin=None, stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE)