libraries/muParser: Fix tarball handling.

Signed-off-by: David Spencer <baildon.research@googlemail.com>

libraries/muParser/muParser.SlackBuild

@@ -62,12 +62,12 @@ set -e
 rm -rf $PKG
 mkdir -p $TMP $PKG $OUTPUT
 cd $TMP
-rm -rf $SRCNAM-$SRCVER
+rm -rf $SRCNAM-$VERSION
 
 if [ -e $CWD/$SRCVER.tar.gz ]; then
   tar xvf $CWD/$SRCVER.tar.gz
 else
-  tar xvf $CWD/$SRCNAM-$SRCVER.tar.gz
+  tar xvf $CWD/$SRCNAM-$VERSION.tar.gz
 fi
 
 cd $SRCNAM-$VERSION