Fix the scanning on non-APEX devices.

On devices not supporting APEX the preInstalledApexPath is always equals
to "/system" with no trailing slash.

Test: atest ApkInApexTests; made non-APEX device boot
Merged-In: I238e88684f48981c44e7152f97b4ca16bed6d166
Change-Id: I238e88684f48981c44e7152f97b4ca16bed6d166
1 file changed