Added integer uint32_t

[Jamaika1]

snappy.cc:1693:28: warning: comparison of integer expressions of different signedness: 'uint32_t' {aka 'unsigned int'} and 'int' [-Wsign-compare]
 1693 |     if (CalculateNeeded(i) != (char_table[i] >> 11) + 1) return false;
      |         ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

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