C++: Accept test changes for is_constexpr

Generated copy and move constructors may now be marked as constexpr.

Author: igfoo

cpp/ql/test/library-tests/specifiers2/specifiers2.expected

@@ -62,13 +62,17 @@
 | Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | extern |
 | Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | inline |
 | Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | inline |
+| Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | is_constexpr |
+| Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | is_constexpr |
 | Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | public |
 | Function | specifiers2pp.cpp:29:7:29:7 | operator= | operator= | public |
 | Function | specifiers2pp.cpp:33:5:33:18 | fun | fun | public |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | extern |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | extern |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | inline |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | inline |
+| Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | is_constexpr |
+| Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | is_constexpr |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | public |
 | Function | specifiers2pp.cpp:35:7:35:7 | operator= | operator= | public |
 | Function | specifiers2pp.cpp:40:12:40:18 | someFun | someFun | extern |