PicSphere: First batch of enhancements [2/2]

This patch:
- Enable the building of cpfind, multiblend, pto_gen
  and pto_var
- Add linefind and multiblend source
- Add a popen JNI helper
- Remove lots of debugging messages
- Remove hacks of what was supposed to be the
  source of freezes

Change-Id: I3c26bfe5a51dd26fc9aaa77bb7c1c2655101689b
Merge commit 'refs/changes/39/48439/6' of http://review.cyanogenmod.org/CyanogenMod/android_external_Focal into cm-10.2
Now that multiblend is being used maybe I don't need to fix this.