Enable _testclinic, _testclinic_limited and xxlimited_3_13 #1185

The three recent extension modules, _testclinic, _testclinic_limited and xxlimited_3_13 are not built on Unix platforms. On Windows the first two are explicitly disabled. On Unix they are disabled implicitly as entires for them do not exist in cpython-unix/extension-modules.yml until #1180.

For testing the standard library all three of these are needed for complete coverage. They are not needed for normal Python execution. These would be called if --pgo-extended as used for profiling.

These modules should only be included in a subset of the supported Python versions

• _testclinic : 3.12+
• _testclinic_limited: 3.13+
• xxlimited_3_13 : 3.15+