[NFC] Add test for (incorrect) behavior of swift-demangle.

Author: varungandhi-apple

test/Demangle/Inputs/manglings.txt

@@ -357,6 +357,8 @@ $s3red4testyAA3ResOyxSayq_GAEs5ErrorAAq_sAFHD1__HCg_GADyxq_GsAFR_r0_lF ---> red.
 $s3red4testyAA7OurTypeOy4them05TheirD0Vy5AssocQzGAjE0F8ProtocolAAxAA0c7DerivedH0HD1_AA0c4BaseH0HI1_AieKHA2__HCg_GxmAaLRzlF ---> red.test<A where A: red.OurDerivedProtocol>(A.Type) -> red.OurType<them.TheirType<A.Assoc>>
 $s17property_wrappers10WithTuplesV9fractionsSd_S2dtvpfP ---> property wrapper backing initializer of property_wrappers.WithTuples.fractions : (Swift.Double, Swift.Double, Swift.Double)
 $sSo17OS_dispatch_queueC4sync7executeyyyXE_tFTOTA ---> {T:$sSo17OS_dispatch_queueC4sync7executeyyyXE_tFTO} partial apply forwarder for @nonobjc __C.OS_dispatch_queue.sync(execute: () -> ()) -> ()
+$s4main1gyySiXCvp ---> main.g : (Swift.Int) -> ()
+$s4main1gyySiXBvp ---> main.g : (Swift.Int) -> ()
 $sxq_Idgnr_D ---> @differentiable @callee_guaranteed (@in_guaranteed A) -> (@out B)
 $sxq_Ilgnr_D ---> @differentiable(linear) @callee_guaranteed (@in_guaranteed A) -> (@out B)
 $sS3fIedgyywd_D ---> @escaping @differentiable @callee_guaranteed (@unowned Swift.Float, @unowned @noDerivative Swift.Float) -> (@unowned Swift.Float)