Revert "Drop principal redefinition"

This reverts commit 66f2485.

Author: antonio-rojas

src/sage/interfaces/maxima_lib.py

@@ -164,6 +164,7 @@
 ecl_eval("(initialize-runtime-globals)")
 ecl_eval("(setq $nolabels t))")
 ecl_eval("(defun add-lineinfo (x) x)")
+ecl_eval('(defun principal nil (cond ($noprincipal (diverg)) ((not *pcprntd*) (merror "Divergent Integral"))))')
 ecl_eval("(remprop 'mfactorial 'grind)")  # don't use ! for factorials (#11539)
 ecl_eval("(setf $errormsg nil)")