* configure.py : Detect java and perl scripts in a general way.

* configure.py : Detect java and perl scripts in a general way.

Issues #6339 and #7579 were fixed by specific code targeting those
RC entries. This commit fixes the detection of java and perl scripts
in a general way. As a result:

  - The detections of jfig3-itext.jar and jfig3.jar, which where
    previously overlooked, are now also fixed, and
  - Future additions of java and perl scripts to configure.py are
    straight forward.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@39699 a592a061-630c-0410-9148-cb99ea01b6c8