[lldb][NFC] Check in test case for testing virtual function calls in pointers and references.

[teemperor]

Summary

rdar://38048657 says that the following test case was broken. It seems to have been fixed since then, so
this patch just adds the test case to our test suite to check for regressions.

[davide]

I seem to remember there was a bug where you run the expression twice and the second time it crashes/it's not evaluated correctly [at least this is what I remember talking to Lang ~18 months ago].
If that works, yay for more coverage!

[teemperor]

Seems like the radar was actually for something else (covariant returns), so this needs to be updated (as covariant returns are still broken).

[teemperor]

This was fixed/tested in D73024

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-ptr-vs-ref/Makefile

+LEVEL = ../../../make
+CXX_SOURCES := main.cpp
+include $(LEVEL)/Makefile.rules

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-ptr-vs-ref/TestVirtualPtrVsRef.py

+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(__file__, globals())

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-ptr-vs-ref/main.cpp

+class A {
+public:
+  virtual ~A() {}
+  virtual int Dump() { return 1; }
+};
+
+class B : public A {
+public:
+  virtual ~B() {}
+  virtual int Dump() { return 2; }
+};
+
+int main(int argc, char const *argv[], char const *envp[]) {
+  B ref;
+  A *ptr = &ref;
+  ptr->Dump();
+  return 0; //%self.expect("p ref.Dump()", substrs=['(int)', ' = 2'])
+            //%self.expect("p ptr->Dump()", substrs=['(int)', ' = 2'])
+}