am: stop using "%KEY:iffalse?iftrue%" transforms And the similar "reduced forms" "%KEY:iffalse%" and "%KEY?iftrue%" as well. They are harder to grasp, can be easily reformulated in function of other "plainer" transforms ("?KEY?" and "?!KEY?"), and we'll remove support for them anyway in a later change. * lib/am/data.am, lib/am/libs.am, lib/am/lisp.am, lib/am/ltlib.am, lib/am/progs.am, lib/am/python.am, lib/am/scripts.am: Adjusted not to rely on those kinds of transforms. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>