Update test CH214128.cpp added in #219799 to work in C++20 mode. (#220016)
Internally we have changed our compiler to default to C++20 mode instead
of C++17 which causes the test added in #219799 to fail.
With the test as it currently is, compiling with C++20 mode gives the
following output:
```
GH214128.cpp:3:6: error: expected '>'
3 | i < 0
| ^
GH214128.cpp:3:3: note: to match this '<'
3 | i < 0
| ^
GH214128.cpp:8:1: error: expected unqualified-id
8 | void f() {
| ^
2 errors generated.
```
Note the error on line 8, this is because there is a missing semi-colon
on the statement `i < 0` on line 3. By adding the semicolon at the end
of that line, it allows the parser to continue and generate the expected
warning in the definition of the function `f()` as well as an additional
warning in C++20 mode:
```
GH214128.cpp:3:6: error: expected '>'
3 | i < 0;
| ^
GH214128.cpp:3:3: note: to match this '<'
3 | i < 0;
| ^
GH214128.cpp:3:1: warning: declaration does not declare anything [-Wmissing-declarations]
3 | i < 0;
| ^
GH214128.cpp:9:10: warning: keyword '__is_pod' will be made available as an identifier for the remainder of the translation unit [-Wkeyword-compat]
9 | struct __is_pod; // expected-warning {{keyword '__is_pod' will be made available as an identifier for the remainder of the translation unit}}
| ^
2 warnings and 1 error generated.
```
This change adds the semi-colon at the end of the statement `i < 0`,
adjusts the expected errors/warnings/notes for c++17/c++20 modes and
explicitly tests both the C++17 and C++20 modes.
llvm-project
4b85bb80 - Update test CH214128.cpp added in #219799 to work in C++20 mode. (#220016)
