tests/hash: return non-zero on failure

... and wire up to `make check' now that it's useful.

v2: Really return non-zero on failure.
v3: Initialise ret.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Jan Vesely <jan.vesely@rutgers.edu> (v2)
2 files changed