flow: Allow unused fixmes, for now.

This lets us insert fixmes in a separate commit from the upgrade
that makes them necessary.

Author: gnprice

.flowconfig

@@ -59,7 +59,8 @@ esproposal.optional_chaining=enable
 esproposal.nullish_coalescing=enable
 
 # The main warning is "Unused suppression comment".
-include_warnings=true
+# Temporarily disabled to smooth the RN upgrade.
+# include_warnings=true
 
 module.system=haste
 module.system.haste.use_name_reducers=true