SampleHandler: Fix thread-safety checker warnings.

Fix thread-safety checker warnings.

This merge request affects 1 package:

• PhysicsAnalysis/D3PDTools/SampleHandler

This merge request affects 16 files:

• PhysicsAnalysis/D3PDTools/SampleHandler/CMakeLists.txt
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/GridTools.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/Sample.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/SampleComposite.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/SampleHandler.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/SamplePtr.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/ScanDir.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/ToolsDiscovery.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/ToolsDuplicates.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/ToolsOther.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/Root/fetch.cxx
• PhysicsAnalysis/D3PDTools/SampleHandler/SampleHandler/Sample.h
• PhysicsAnalysis/D3PDTools/SampleHandler/SampleHandler/SampleHandler.h
• PhysicsAnalysis/D3PDTools/SampleHandler/SampleHandler/SamplePtr.h
• PhysicsAnalysis/D3PDTools/SampleHandler/SampleHandler/ToolsDiscovery.h
• PhysicsAnalysis/D3PDTools/SampleHandler/test/gt_hadd.cxx

Adding @krumnack as watcher

added Analysis analysis-review-required main review-pending-level-1 labels

CI Result SUCCESS (hash 65107836)

	AnalysisBase	AthAnalysis
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
AnalysisBase: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 5376] (remote access info)

removed review-pending-level-1 label

added review-approved label

Will approve this OBO analysis shifter as I see nothing controversial with the change.

removed analysis-review-required label

added analysis-review-approved label

merged

mentioned in commit 93c874b8