C++: Drop --clang_vector_types option

The types are already enabled through the specfied gcc version.

Author: jketema

cpp/ql/test/library-tests/structs/compatible_c/c1_gnu.c

@@ -7,4 +7,4 @@ struct Kiwi {
 struct Lemon {
   unsigned int __attribute__ ((vector_size (16))) lemon_x;
 };
-// semmle-extractor-options: -std=c99 --clang --edg --clang_vector_types --gnu_version 40700
+// semmle-extractor-options: -std=c99 --clang --gnu_version 40700

cpp/ql/test/library-tests/structs/compatible_c/c2_gnu.c

@@ -7,4 +7,4 @@ struct Kiwi {
 struct Lemon {
   signed int __attribute__ ((vector_size (16))) lemon_x;
 };
-// semmle-extractor-options: -std=c99 --clang --edg --clang_vector_types --gnu_version 40700
+// semmle-extractor-options: -std=c99 --clang --gnu_version 40700