[Clang] Interpreter test should not depend on system header (#119903)

30ad53b
introduced a new test that includes `<vector>` from the system include
path without honoring environment variables that may provide the path to
C++ standard library. This is not supported in some CI systems because
we don't always have the C++ library in the standard location.

The conventional way of doing includes in the test is through `Inputs`
directory and pass it as an include path.

The `vector` file included in this patch has been shortened, but I have
verified that it works with this test. i.e. the clang repl crashes on
this test in the same way if the fix in
#117475 is reverted.

Author: yuxuanchen1997

clang/test/Interpreter/Inputs/vector

@@ -0,0 +1,10 @@
+#ifndef VECTOR
+#define VECTOR
+namespace std {
+template <typename>
+class vector {
+public:
+  vector();
+};
+} // namespace std
+#endif // VECTOR

clang/test/Interpreter/crash.cpp

@@ -5,7 +5,7 @@
 //
 // RUN: split-file %s %t
 //
-// RUN: %clang++ -std=c++20 -fPIC -c %t/vec.cpp -o %t/vec.o
+// RUN: %clang++ -Xclang -nostdsysteminc -I%S/Inputs/ -std=c++20 -fPIC -c %t/vec.cpp -o %t/vec.o
 // RUN: %clang++ -shared %t/vec.o -o %t/vec.so
 //
 // RUN: cat %t/Test.cpp | LD_LIBRARY_PATH=%t:$LD_LIBRARY_PATH clang-repl