zstd: Big speedup on small dictionary encodes #345
Merged
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All credit goes to @tony2001
As shown in #344 the speed of small dictionary compression tasks (< 32K) can be improved significantly by keeping track of the state of the hash table.
This effectively implements #344 but avoids a penalty for non-dictionary encodes and extends the functionality to the "better" compression mode as well.
This change will also make it easier to remove the copy of the literal dictionary every time an encode starts and have specialized code to deal with this.