mercury: flag_handler: fix incorrect indent on return statement (#23579)

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

@@ -63,7 +63,7 @@ def flag_handler(self, name, flags):
         if self.spec.satisfies('%cce'):
             if name == 'ldflags':
                 flags.append('-Wl,-z,muldefs')
-            return (None, None, flags)
+        return (None, None, flags)
 
     def cmake_args(self):
         """Populate cmake arguments for Mercury."""