c++: add passing testcases [PR120243] These pass now; the first was fixed by r16-1507. PR c++/120243 gcc/testsuite/ChangeLog: * g++.dg/coroutines/torture/pr120243-unhandled-1.C: New test. * g++.dg/coroutines/torture/pr120243-unhandled-2.C: New test. (cherry picked from commit 2492bab503f57f2cf6e08e5c104f7a1d31d34047)