Fix in wscript.

git-svn-id: http://subversion.jackaudio.org/jack/jack2/trunk/jackmp@4090 0c269be4-1314-0410-8aa9-9f06e86f4224

wscript

@@ -164,7 +164,7 @@ def configure(conf):
     else:
         conf.env['LIBDIR'] = conf.env['PREFIX'] + '/lib'
 
-    if Options.options.libdir:
+    if Options.options.mandir:
         conf.env['MANDIR'] = conf.env['PREFIX'] + Options.options.mandir
     else:
         conf.env['MANDIR'] = conf.env['PREFIX'] + '/share/man/man1'