products/common.mk: remove the test statement

for *.apk *.so *.jar and *.xml it results in a
test: too many arguments when there is more than one file,
also it is not needed because the find command finds only
exiting files.

Change-Id: Icbbcc346431f843b63250a66ac77d1392560ea02
Merge "products/common.mk: remove the test statement" into gingerbread