Add error checking for a missing Manifest and for when no perf args are passed.
Add error checking for a missing Manifest and for when no perf args are passed.

Change-Id: Ie8f1c6670d8932ada776d357e3f5f89d719687fa
Tested: Ran script with Testbed

google/fplutil,google/fplutil,google/fplutil,google/fplutil,google/fplutil,google/fplutil