Add local context test for demangling

Author: janbaig

test/Demangle/Inputs/manglings.txt

@@ -378,6 +378,7 @@ $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)
 $s16property_wrapper8MyStructV1xSivpfF ---> property wrapped field init accessor of property_wrapper.MyStruct.x : Swift.Int
+$s4main6myFuncyyF1xL_SivpfF ---> property wrapped field init accessor of x #1 : Swift.Int in main.myFunc() -> ()
 $sSo17OS_dispatch_queueC4sync7executeyyyXE_tFTOTA ---> {T:$sSo17OS_dispatch_queueC4sync7executeyyyXE_tFTO} partial apply forwarder for @nonobjc __C.OS_dispatch_queue.sync(execute: () -> ()) -> ()
 $s4main1gyySiXCvp ---> main.g : @convention(c) (Swift.Int) -> ()
 $s4main1gyySiXBvp ---> main.g : @convention(block) (Swift.Int) -> ()