[clang] Objective C: use C++ exceptions on MinGW+GNUstep (PR #77255)

[Saleem Abdulrasool via cfe-commits]

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@@ -3993,7 +4009,9 @@ void CGObjCGNU::EmitThrowStmt(CodeGenFunction &CGF,
     ExceptionAsObject = CGF.ObjCEHValueStack.back();
     isRethrow = true;
   }
-  if (isRethrow && usesSEHExceptions) {
+  if (isRethrow &&
+      (usesSEHExceptions || (CGM.getTarget().getTriple().isOSCygMing() &&
+                             isRuntime(ObjCRuntime::GNUstep, 2)))) {
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compnerd wrote:

Does it make sense to introduce a `usesCxxExceptions` variable?

https://github.com/llvm/llvm-project/pull/77255