Resolve Coverity 1432392 Unintentional integer overflow
Resolve Coverity 1432392 Unintentional integer overflow

Unintentional integer overflow (OVERFLOW_BEFORE_WIDEN)
overflow_before_widen: Potentially overflowing expression:
cdict->dictContentSize * 6U
with type unsigned int (32 bits, unsigned) is evaluated using 32-bit
arithmetic, and then used in a context that expects an expression of
type U64 (64 bits, unsigned).

Cyan4973/zstd,Cyan4973/zstd,Cyan4973/zstd,Cyan4973/zstd,Cyan4973/zstd