Add CHECK_INT64_EQ function to avoid operand size ambiguities.

Add CHECK_INT64_EQ function to avoid operand size ambiguities.

Committed: http://code.google.com/p/v8/source/detail?r=3016

[William Hesse, 2009-10-03 13:30:48]

The casts aren't necessary, but they make it explicit.

[William Hesse, 2009-10-03 13:45:22]

TBR=plesner@chromium.org

To have CHECK_EQ for both 32-bit and 64-bit ints, we need to handle the
following cases, on both 32- and 64- bit platforms:
Comparing int32_t to uint32_t, where we want to reinterpret them as both int32_t
Comparing int32_t to intptr_t - this would need explicit casts in all cases.
Comparing int64_t to intptr_t

So I think a separate CHECK_INT64_EQ is safer than overloading, or having only a
64-bit CHECK_EQ, with all integer types upconverted (that breaks comparisons
between int32_t and uint32_t that want to reinterpret then as 32-bit patterns).