[embedded] -no-allocations should be a flag without arguments

Author: kubamracek

include/swift/Option/Options.td

@@ -872,9 +872,8 @@ def save_optimization_record_passes :
            "the generated optimization record "
            "(by default, include all passes)">, MetaVarName<"<regex>">;
 
-def no_allocations : Separate<["-"], "no-allocations">,
+def no_allocations : Flag<["-"], "no-allocations">,
   Flags<[FrontendOption, HelpHidden]>,
-  MetaVarName<"<n>">,
   HelpText<"Diagnose any code that needs to heap allocate (classes, closures, etc.)">;
 
 // Platform options.