mark vipsprofile as python2

Some distros have python3 as the default, so make vipsprofile explicitly
python2, thanks ioquatix.

See https://github.com/jcupitt/libvips/issues/667

ChangeLog

@@ -2,6 +2,7 @@
 - tiff read with start page > 0 could break edge tiles or strips
 - raise b64 limit to allow for huge profiles (thanks jaume)
 - fix error return in blob save (thanks jaume)
+- tag vipsprofile as py2 (thanks ioquatix)
 
 23/4/17 started 8.5.5
 - doc polishing

tools/vipsprofile

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python2
 
 import re
 import math