Restrict the cases when we profile guided compile an apk

Do not use profile guided compilation if the apk is loaded by another
app. The decision if an apk was used or not by another app is done
by looking into the foreign profile directory. Apks which where
loaded in others apps will have a file marker in the profile directory.
The marker is  named after the canonical location of the apk file where
'/' is replaced by '@'.

Also, refactor the profile paths to the Environment.

Bug: 27334750
Bug: 26080105
Change-Id: Ic2ac5a7a231670ecb4462166c34fdd5b4c631178