minikconf: don't print CONFIG_FOO=n lines

qemu in general doesn't define CONFIG_FOO if it's false.  This also
helps with the dumb kconfig parser from meson, as source_set considers
any non-empty value as true.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/minikconf.py

@@ -702,8 +702,8 @@ if __name__ == '__main__':
 
     config = data.compute_config()
     for key in sorted(config.keys()):
-        if key not in external_vars:
-            print ('CONFIG_%s=%s' % (key, ('y' if config[key] else 'n')))
+        if key not in external_vars and config[key]:
+            print ('CONFIG_%s=y' % key)
 
     deps = open(argv[2], 'w')
     for fname in data.previously_included: