E3-517: Cleanup `make vars`
There are a number of variables printed when one runs make vars
that are not particularly necessary, and so this removes them.
Note that this process is sorted out quasi-automatically: in the file RULES_VARS
we have the line
E3_MODULES_VARIABLES:=$(sort $(filter-out $(VARS_EXCLUDES) VARS_EXCLUDES,$(.VARIABLES)))
which means that in order to skip printing a variable we have to just add it to VARS_EXCLUDES
.
Some other assorted cleanup has been performed as well.