configure: added a test for the existence of the sourceme/makefile file

to not return an error in case of ./configure --help

configure

@@ -4,7 +4,7 @@ rm -f sourceme.sh Makefile.conf
 
 cd autoconf
 ./configure "${@}"
-cp Makefile.conf ../
-cp sourceme.sh ../
+if [ -e Makefile.conf ]; then cp Makefile.conf ../; fi
+if [ -e sourceme.sh ]; then cp sourceme.sh ../; fi