HuffmanTableVector::getSymbol(): use early return when looking for prefix.
HuffmanTableVector::getSymbol(): use early return when looking for prefix.

Makes HuffmanTableVectorFuzzer-BitPumpLSB-NoFullDecode
about ~1k exec/s faster (2.7 -> 3.7)

Though the HuffmanTableLUT is well into 12k exec/s

LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed