IMPALA-4983: Compile LZ4 in release mode
IMPALA-4983: Compile LZ4 in release mode

LZ4 was not compiled (apparently ever?) with optimization enabled. In
recent versions this lead to a regression in compression time that was
noticeable vs previous LZ4 versions. With optimization enabled, the
regression appears to vanish.

Change-Id: I8bd113822dfc4df2d76c4393c4b3b3550066dd18

cloudera/native-toolchain,mjacobs/native-toolchain,timarmstrong/native-toolchain,cloudera/native-toolchain,cloudera/native-toolchain