Gnuplot fix 16928 (#16929)

* gnuplot: Fix for #16928

Dependency for --with-wx flag mistyped (should be wxwidgets)

* Revert "gnuplot: Fix for #16928"

This reverts commit 2b85814e5ccf5c9b2c70c7959994e89c18fdc3d8.

* gnuplot: Fix for #16928

Dependency spec for --with-wx flag mistyped (should be wxwidgets, not
wx)

var/spack/repos/builtin/packages/gnuplot/package.py

@@ -122,7 +122,7 @@ def configure_args(self):
             options.append('--with-qt=no')
 
         if '+wx' in spec:
-            options.append('--with-wx=%s' % spec['wx'].prefix)
+            options.append('--with-wx=%s' % spec['wxwidgets'].prefix)
         else:
             options.append('--disable-wxwidgets')