luaexpatutils: add .hash file
Fixes:
http://autobuild.buildroot.org/results/4f6/4f6439f421809090c874e24055348e3f30b2e2b0/
http://autobuild.buildroot.org/results/bd4/bd4a1db0136ee65f325d1fd9826dedb23986134d/
Similar to jquery-keyboard, it seems the luaexpatutiles tarball on the
autobuilder is corrupt. Fix it by adding a .hash file so it falls back to
our s.b.o mirror.
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>