Use a wider integer for the parser stack.

The MSVC10 64-bit build was complaining about type narrowing,
because the union that the parser used as its value type had
and "unsigned int" member that was narrower than the union.
It seems best to use a 64-bit integer for 64-bit platforms.

Change-Id: Idc198283f2d7865a33438bfc8ae0f9c6279ecbba
Merge topic 'parser-union-type' into master

d1f7875c Use a wider integer for the parser stack.