Variables by these names are only used from the local wscript and when
running "waf configure", which already for other reasons only can run at
the top-level.
These variables are thus not mandatory and not used.
Done with ad hoc scripting hacks processing unused imports found by pyflakes:
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Logs.* but unused' | cut -d: -f1 | while read f; do sed -i 's/^import waflib.Logs as Logs,/import/g' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Options.* but unused' | cut -d: -f1 | while read f; do sed -i 's/import waflib.Options as Options, /import /g' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Options.* but unused' | cut -d: -f1 | while read f; do sed -i 's/^from waflib import Options,/from waflib import/g' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep ' imported but unused$' | sed "s/^\([^:]*\):[0-9]*:[0-9]* '\(.*\)'.*/\1 \2/g" | while read f lib; do sed -i "/^import $lib$/d" $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Options.* but unused' | cut -d: -f1 | while read f; do sed -i '/from waflib import Options$/d' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.TaskGen.* but unused' | cut -d: -f1 | while read f; do sed -i '/from waflib import TaskGen$/d' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Task.Task.* but unused' | cut -d: -f1 | while read f; do sed -i '/^from waflib.Task import Task$/d' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Tools.winres.* but unused' | cut -d: -f1 | while read f; do sed -i '/^from waflib.Tools import winres$/d' $f; done
for f in $( find * -name wscript ); do echo; pyflakes $f; done | grep 'waflib.Utils.* but unused' | cut -d: -f1 | while read f; do sed -i '/^import waflib.Utils as Utils$/d' $f; done
uselib is no longer implicit (inherited by .use). This is still incomplete,
some uselibs for non-linux variants may be missing.
bld.is_defined("HAVE_XXX") also no longer works and will have to be
changed (I think to bld.env["HAVE_XXX"]) in countless places.
