Fixed ProguardTest.cpp
Fixed ProguardTest.cpp

Summary: This test doesn't pass on my Mac (the oldest version of the API available on my Android SDK is 23). Failure to load the library goes unnoticed, as the return value of load_jar_file isn't checked.

Reviewed By: emma0303, maxmg22

Differential Revision: D5397155

fbshipit-source-id: e4035bfb83df97d81bd0538dc1ad46717416e23e

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex