C++: Update vector type test to reflect it uses old-clang features

These features are no longer available and the frontend does stricter checking
on this.

cpp/ql/test/library-tests/vector_types/vector_types.cpp

@@ -1,6 +1,6 @@
+// semmle-extractor-options: --edg --clang --edg --clang_version --edg 30801
 // Compilable with: clang --std=c++0x -msse4.1 vector_types.cpp
 // (some bits also compilable with gcc)
-
 int printf(...);
 
 typedef float v4f __attribute__((vector_size(16)));