json-c: add .hash file
Fixes:
http://autobuild.buildroot.org/results/38f/38fd47a81cc2a6fc515158692af4e2b62f4a965f/
http://autobuild.buildroot.org/results/ecc/ecc4ca7fdda173faf042dfe991073d8c5e9af4d6/
Similar to jquery-keyboard, it seems the json-c 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>
Peter Korsgaard