Fix FROM_PACKAGE checks for novnc and spice

The logic for installing novnc and spice from packages is broken,
which makes it impossible to install from git, which makes bug
1248923 more serious.

Change-Id: I9ae722a5470a16555bca9018da342485f6d3e896
Related-Bug: 1248923
Merge "Fix FROM_PACKAGE checks for novnc and spice"