Update makesrcdist: fix packaging bug

The previous version didn't delete the docs before the source files
were packed which resulted in too big release tarballs.

Notes:
 (1) Release 1.4.1 has been updated (files were replaced) so all
     further downloads are not affected.
 (2) The git commits on tag release-1.4.1 do not include this commit
     but this is OK. This will be in the next release.
 (3) makesrcdist itself is not packed in the source tarballs anyway.

makesrcdist

@@ -212,10 +212,7 @@ if test $# != 0 -a "x$1" != "xsnapshot"; then
 fi
 
 echo "Removing documentation..."
-rm -rf fltk-$version/documentation/html/
-rm -f fltk-$version/documentation/fltk.pdf
-rm -rf fltk-$version/fluid-documentation/html/
-rm -f fltk-$version/fluid-documentation/fltk.pdf
+rm -rf fltk-$version/$DOC_TEMPDIR
 
 echo "Making UNIX (.tar.gz) distribution..."
 $TAR czf fltk-$fileversion-source.tar.gz fltk-$version