gh-108494: Don't build _testclinic_limited with TraceRefs

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If Python is built with ./configure --with-trace-refs, don't build the _testclinic_limited extension. The limited C API (Py_LIMITED_API) is not compatible with Py_TRACE_REFS.

• Issue: Add support for the limited C API to Argument Clinic #108494

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Currently, building Python on the TraceRefs buildbot fails with:

gcc -fno-strict-overflow -Wsign-compare -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -g -Og -Wall -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I. -I./Include -fPIC -c ./Modules/_testclinic_limited.c -o Modules/_testclinic_limited.o In file included from ./Include/Python.h:44, from ./Modules/_testclinic_limited.c:7: ./Include/object.h:62:4: error: #error Py_LIMITED_API is incompatible with Py_TRACE_REFS 62 | # error Py_LIMITED_API is incompatible with Py_TRACE_REFS | ^~~~~ make: *** [Makefile:3139: Modules/_testclinic_limited.o] Error 1 

link: https://buildbot.python.org/all/#/builders/484/builds/3914

You can reproduce with:

make distclean ./configure --with-pydebug --with-trace-refs && make 

With this change, the build completes as expected and test_clinic pass:

$ make && ./python -m test -v test_clinic The following modules are *disabled* in configure script: _testclinic_limited xxlimited xxlimited_35 (...) test_my_int_func (test.test_clinic.LimitedCAPIFunctionalTest.test_my_int_func) ... skipped '_testclinic_limited is missing' test_my_int_sum (test.test_clinic.LimitedCAPIFunctionalTest.test_my_int_sum) ... skipped '_testclinic_limited is missing' (...) 

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cc @erlend-aasland

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Merged, thanks for the review.