Re-enable 2.8.0 cc @Endilll

Author: mattgodbolt

bin/yaml/cpp.yaml

@@ -940,8 +940,7 @@ compilers:
             check_exe: bin/clang --version
           - name: assertions-2.7.0
             check_exe: bin/clang --version
-          # temporarily disabled pending a fix of its build (clang++ symlink is broken)
-          # - assertions-2.8.0
+          - assertions-2.8.0
           - assertions-2.9.0
           - assertions-3.0.0
           - assertions-3.1.0