Pass the same set of object files when retrying linking for cgo

[skirino]

With the latest main branch, pants test src/python/pants/backend/go/util_rules/cgo_test.py:tests fails in my environment:

============================= test session starts ==============================
collecting ... collected 5 items

src/python/pants/backend/go/util_rules/cgo_test.py::test_cgo_compile PASSED [ 20%]
src/python/pants/backend/go/util_rules/cgo_test.py::test_cgo_with_cxx_source FAILED [ 40%]
src/python/pants/backend/go/util_rules/cgo_test.py::test_cgo_with_objc_source FAILED [ 60%]
src/python/pants/backend/go/util_rules/cgo_test.py::test_cgo_with_fortran_source FAILED [ 80%]
src/python/pants/backend/go/util_rules/cgo_test.py::test_cgo_with_embedded_static_library PASSED [100%]

=================================== FAILURES ===================================

The 3 tests fail with the same linker error:

ValueError: cgo binary link failed:
stdout:

stderr:
Undefined symbols for architecture arm64:
  "_main", referenced from:
      <initial-undefines>
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

(found this issue during playing around the tests in #23439)

In cgo.py, linking of object files are retried with additional linker options:
https://github.com/pantsbuild/pants/blob/main/src/python/pants/backend/go/util_rules/cgo.py#L500-L559
For relatively simple case, linking succeeds at the 1st try. In the case of ObjC, C++ and Fortran tests, linking fails (due to lack of the language's stdlib?) and retried. _main (cgo-generated dummy function) resides in _cgo_main.o file and is required by the linker, but the object file is not included in the linker flags at the 2nd try.

My environment:

• OS: macOS 15.7.7
• gcc: clang-1700.6.4.2
• python: 3.14.6
• go: 1.26.2