Template ambiguity under HP UX.

Under HP UX (gcc 4.6.0) compiler reported :
NCollection_DefaultHasher.hxx:34:32: error: call of overloaded
'HashCode(const unsigned int&, Standard_Integer&)' is ambiguous.
It seems there is no implementation of HashCode & IsEqual for
Standard_Utf32Char object.Passed it as a Standard_Integer in order
to mask and solve this error.