Fix bug preventing multi-module native coverage.

Fix a whitespace bug causing coverage to be enabled on all modules
whenever more than one module is specified. This is caused by
comparing whitespace to the empty string, which are not equal. Fix
by stripping the output to check for path matches.

Test: tested using local build with coverage enabled on NFC, lights
Change-Id: I61a775cfd135f94ea1e1ee9fdbed3c64c5bb1a2e