Added tests to _testingUtils.c (currently failing due to a bug in printing 64bit numbers)
Fixing this bug will expose a failing test case for Concrete/ConstantExpr.ll
Fixed test/Concrete/ConstantExpr.ll

The difference between a 64bit pointer truncated to 32 bits and the
original 64bit pointer would never be 0 if any of the high 32bits in
the pointer were test. If lli and klee had a different value for the
top 32bits of the address this test would be marked as failing.

Due to the 64bit printing buf in _testingUtils this was not exposed before.

The fix clears the top 32bits of the difference.
Fix the bug in printing 64bit numbers, set the test to expect passing. Changed _testingUtils to use stdint.h