Fix unzip on sdk_mac build

Recent CL added a flag to an unzip command which does not restore
the timestamps of extracted files. This is necessary because the
extracted files are the output of the rule and thus the timestamp
must be newer than the timestamp of the inputs.

Unfortunately, the sdk_mac build has an old version of UnZip (5.52
vs 6.0) which does not support the flag. Replace it with find|touch.

Test: m
Change-Id: Ib1f218af4547a1d604b46e68b6ef50d45cb91ee9