Don't set GCState to 1 in PInvoke Epilog

The comment indicated this was necessary to keep the FrameListRoot live, but the code generated by `CreateFrameLinkUpdate` will do that if needed.

Fix dotnet#38192

src/coreclr/src/jit/lower.cpp

@@ -4055,20 +4055,6 @@ void Lowering::InsertPInvokeMethodEpilog(BasicBlock* returnBB DEBUGARG(GenTree*
     // Example3: GT_JMP.  After inserting PME execution order would be: PME, GT_JMP
     //           That is after PME, args for GT_JMP call will be setup.
 
-    // TODO-Cleanup: setting GCState to 1 seems to be redundant as InsertPInvokeCallProlog will set it to zero before a
-    // PInvoke call and InsertPInvokeCallEpilog() will set it back to 1 after the PInvoke.  Though this is redundant,
-    // it is harmeless.
-    // Note that liveness is artificially extending the life of compLvFrameListRoot var if the method being compiled has
-    // PInvokes.  Deleting the below stmnt would cause an an assert in lsra.cpp::SetLastUses() since compLvFrameListRoot
-    // will be live-in to a BBJ_RETURN block without any uses.  Long term we need to fix liveness for x64 case to
-    // properly extend the life of compLvFrameListRoot var.
-    //
-    // Thread.offsetOfGcState = 0/1
-    // That is [tcb + offsetOfGcState] = 1
-    GenTree* storeGCState = SetGCState(1);
-    returnBlockRange.InsertBefore(insertionPoint, LIR::SeqTree(comp, storeGCState));
-    ContainCheckStoreIndir(storeGCState->AsIndir());
-
     // Pop the frame if necessary. This always happens in the epilog on 32-bit targets. For 64-bit targets, we only do
     // this in the epilog for IL stubs; for non-IL stubs the frame is popped after every PInvoke call.
     CLANG_FORMAT_COMMENT_ANCHOR;

src/coreclr/tests/src/Interop/UnmanagedCallersOnly/UnmanagedCallersOnlyTest.cs

@@ -42,8 +42,7 @@ public static int Main(string[] args)
             TestUnmanagedCallersOnlyValid();
             TestUnmanagedCallersOnlyValid_OnNewNativeThread();
             TestUnmanagedCallersOnlyValid_PrepareMethod();
-            // Fails due to https://github.com/dotnet/runtime/issues/38192
-            //TestUnmanagedCallersOnlyMultipleTimesValid();
+            TestUnmanagedCallersOnlyMultipleTimesValid();
             NegativeTest_NonStaticMethod();
             NegativeTest_ViaDelegate();
             NegativeTest_NonBlittable();