DeflateDecompressorBenchmark: don't forget to explicitly link to ZLIB
DeflateDecompressorBenchmark: don't forget to explicitly link to ZLIB

Since rawspeed is built as a static library, we happened to get implicitly
linked to it, but that's fragile.

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