Windows: always emit definitions of JITed "weak" variables
Windows: always emit definitions of JITed "weak" variables

Fixes test failures (crashes) in
    projectroot.test.test_stressiterators_interpreted
    projectroot.roottest.cling.dict.roottest_cling_dict_assertTmpltDefArgCtor
    projectroot.test.test_stresshistogram_interpreted
    projectroot.roottest.root.meta.roottest_root_meta_runnamespace_auto

root-mirror/cling,root-mirror/cling,root-mirror/cling,root-mirror/cling,root-mirror/cling,root-mirror/cling