melt src/tools/tools.pro into src/src.pro

this is done mainly to resolve spurious dependencies, in preparation
for making some tools not bootstrapped in native builds.

as a nice side effect, there is even more parallelization possible now.

Change-Id: I779cf0059c98c65aba8510bf3d24fdab4eeaa863
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>