[Core][TReentrantRWLock] Add missing variable definition

[stwunsch]

I really wonder why this is only picked up by windows?

Edit: It's the macro 😬

[phsft-bot]

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos7-multicore/default, ROOT-fedora30/cxx14, ROOT-fedora31/noimt, ROOT-ubuntu16/nortcxxmod, mac1014/python3, mac1015/cxx17, windows10/cxx14
How to customize builds

[phsft-bot]

Build failed on ROOT-fedora31/noimt.
Running on root-fedora-31-1.cern.ch:/build/workspace/root-pullrequests-build
See cdash.
See console output.

Warnings:

• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: variable ‘local’ set but not used [-Wunused-but-set-variable]
• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: variable ‘local’ set but not used [-Wunused-but-set-variable]
• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: variable ‘local’ set but not used [-Wunused-but-set-variable]
• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: unused variable ‘local’ [-Wunused-variable]
• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: unused variable ‘local’ [-Wunused-variable]
• [2020-09-18T11:30:07.788Z] /build/workspace/root-pullrequests-build/root/core/thread/src/TReentrantRWLock.cxx:323:12: warning: unused variable ‘local’ [-Wunused-variable]

Failing tests:

• projectroot.roottest.root.io.treeForeign.roottest_root_io_treeForeign_testForeignDraw
• projectroot.roottest.root.meta.roottest_root_meta_drawing

[phsft-bot]

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos7-multicore/default, ROOT-fedora30/cxx14, ROOT-fedora31/noimt, ROOT-ubuntu16/nortcxxmod, mac1014/python3, mac1015/cxx17, windows10/cxx14
How to customize builds

[phsft-bot]

Build failed on ROOT-fedora31/noimt.
Running on root-fedora-31-1.cern.ch:/build/workspace/root-pullrequests-build
See cdash.
See console output.

Failing tests:

• projectroot.roottest.root.io.treeForeign.roottest_root_io_treeForeign_testForeignDraw
• projectroot.roottest.root.meta.roottest_root_meta_drawing

[phsft-bot]

Build failed on windows10/cxx14.
Running on null:C:\build\workspace\root-pullrequests-build
See cdash.
See console output.

Errors:

• [2020-09-18T12:04:22.487Z] C:\build\workspace\root-pullrequests-build\root\core\thread\src\TReentrantRWLock.cxx(323,1): error C2664: 'bool ROOT::Internal::UniqueLockRecurseCount::IsNotCurrentWriter(ROOT::Internal::UniqueLockRecurseCount::local_t &)': cannot convert argument 1 from 'ROOT::Internal::UniqueLockRecurseCount::local_t' to 'ROOT::Internal::UniqueLockRecurseCount::local_t &' [C:\build\workspace\root-pullrequests-build\build\core\thread\Thread.vcxproj]

[phsft-bot]

Build failed on mac1014/python3.
Running on macitois21.cern.ch:/build/jenkins/workspace/root-pullrequests-build
See cdash.
See console output.

Failing tests:

• projectroot.roottest.root.meta.evolution.roottest_root_meta_evolution_execMixedBaseClass_v2
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_RunMyClass
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_execTmpltD
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_execTmpltD32
• projectroot.roottest.root.io.transient.base.roottest_root_io_transient_base_WriteFile
• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache
• projectroot.roottest.root.tree.fastcloning.roottest_root_tree_fastcloning_runabstract_datageneration
• projectroot.roottest.root.tree.fastcloning.roottest_root_tree_fastcloning_runoutoforder_datageneration
• projectroot.roottest.root.tree.fastcloning.roottest_root_tree_fastcloning_make_CloneTree
• projectroot.bindings.pyroot.pythonizations.test.pyunittests_pyroot_root_module

And 920 more

[phsft-bot]

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos7-multicore/default, ROOT-fedora30/cxx14, ROOT-fedora31/noimt, ROOT-ubuntu16/nortcxxmod, mac1014/python3, mac1015/cxx17, windows10/cxx14
How to customize builds

[phsft-bot]

Build failed on ROOT-fedora31/noimt.
Running on root-fedora-31-1.cern.ch:/build/workspace/root-pullrequests-build
See cdash.
See console output.

Failing tests:

• projectroot.roottest.root.io.treeForeign.roottest_root_io_treeForeign_testForeignDraw
• projectroot.roottest.root.meta.roottest_root_meta_drawing

[phsft-bot]

Build failed on mac1014/python3.
Running on macitois21.cern.ch:/build/jenkins/workspace/root-pullrequests-build
See cdash.
See console output.

Failing tests:

• projectroot.roottest.root.io.stdarray.roottest_root_io_stdarray_colWiseWrite_1
• projectroot.roottest.root.io.uniquePointer.roottest_root_io_uniquePointer_readPtrColls
• projectroot.roottest.root.meta.evolution.roottest_root_meta_evolution_execBaseClass_v2
• projectroot.roottest.root.meta.evolution.roottest_root_meta_evolution_execMixedBaseClass_v2
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_RunMyClass
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_execTmpltD
• projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_execTmpltD32
• projectroot.roottest.root.tree.cache.roottest_root_tree_cache_autocache
• projectroot.roottest.root.tree.fastcloning.roottest_root_tree_fastcloning_runabstract_datageneration
• projectroot.roottest.root.io.transient.base.roottest_root_io_transient_base_WriteFile

And 924 more