We can start removing out directories again in multiproduct_kati, since
the opendir bug has been fixed.
Add --color_warnings to the Kati command line. Since this is different
from Make, take this opportunity to reorder the command line to make
more sense. This wasn't done before because kati forces a regen whenever
the command line changes.
Test: USE_SOONG_UI=true m -j blueprint_tools
Change-Id: I5ad03359fbc16db482722946202297c1ae0f2b90