Drop grep and lipo -info from check_libcompat for Darwin

lipo supports -verify_arch option on Darwin target, which works
for fat and non-fat binaries. -verify_arch exists with status 0
if specified architecture is available in the binary.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Signed-off-by: Fons Rademakers <Fons.Rademakers@cern.ch>