[llvm] [Offload] Add MPI Plugin (PR #90890)

[Shilei Tian via llvm-commits]

================
@@ -0,0 +1,11 @@
+#include "EventSystem.h"
+
+int main() {
----------------
shiltian wrote:

```suggestion
int main(int argc, char *argv[]) {
```

https://github.com/llvm/llvm-project/pull/90890