libdeflate decompresses much faster than gzip.

Example:

~/d/openwrt> time gzip -dc dl/cmake-3.25.1.tar.gz > /dev/null

________________________________________________________
Executed in    1.01 secs      fish           external
   usr time  912.61 millis    1.67 millis  910.94 millis
   sys time   32.21 millis    0.25 millis   31.96 millis

~/d/openwrt> time libdeflate-gzip -dc dl/cmake-3.25.1.tar.gz > /dev/null

________________________________________________________
Executed in  523.04 millis    fish           external
   usr time  415.48 millis    1.07 millis  414.41 millis
   sys time  107.74 millis    0.15 millis  107.59 millis

~/d/openwrt> time gzip -dc dl/tessdata-4.1.0.tar.gz > /dev/null

________________________________________________________
Executed in    8.99 secs    fish           external
   usr time    8.90 secs  530.00 micros    8.90 secs
   sys time    0.07 secs   63.00 micros    0.07 secs

~/d/openwrt> time libdeflate-gzip -dc dl/tessdata-4.1.0.tar.gz > /dev/null

________________________________________________________
Executed in    2.74 secs    fish           external
   usr time    2.38 secs  537.00 micros    2.38 secs
   sys time    0.35 secs   66.00 micros    0.35 secs

Place libdeflate into tools-core as it is needed to decompress other
archives.

Signed-off-by: Rosen Penev <rosenp@gmail.com>