don't prepend the paths, as this will only mess up building of
subsequent modules (e.g., building qtdeclarative against an installed
qtbase would pick up the headers from the qtdeclarative previously
installed into the same directory as qtbase).
for frameworks this was a rather pointless exercise in the first place,
as their headers are properly isolated anyway.
however, make sure that we don't add system locations to the search
paths, as this is a) unnecessary and b) messes up subsequent libraries
in non-standard locations which want to shadow versions in standard
locations (pkg-config .pc files which add standard paths are considered
broken as well).
Change-Id: Ie1dc65d4767e98e1df6e49012505141935a6c704
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>
5d1b4c79d2