Updates to Brotli compression format, decoder and encoder

This commit contains a batch of changes that were made to the Brotli
compression algorithm in the last month. Most important changes:

   * Format change: don't push distances representing static dictionary words to the distance cache.
   * Fix decoder invalid memory access bug caused by building a non-complete Huffman tree.
   * Add a mode parameter to the encoder interface.
   * Use different hashers for text and font mode.
   * Add a heuristics to the hasher for skipping non-compressible data.
   * Exhaustive search of static dictionary during backward reference search.

brotli/enc/literal_cost.h

@@ -26,11 +26,11 @@ namespace brotli {
 // ringbuffer (data, mask) will take entropy coded and writes these estimates
 // to the ringbuffer (cost, mask).
 void EstimateBitCostsForLiterals(size_t pos, size_t len, size_t mask,
-                                 const uint8_t *data,
+                                 size_t cost_mask, const uint8_t *data,
                                  float *cost);
 
 void EstimateBitCostsForLiteralsUTF8(size_t pos, size_t len, size_t mask,
-                                     const uint8_t *data,
+                                     size_t cost_mask, const uint8_t *data,
                                      float *cost);
 
 }  // namespace brotli