DerivationFramework cppcheck related fixes

cppcheck warnings of the form

Either the condition 'x==nullptr' is redundant or there is possible null pointer dereference: x.

Prefer prefix ++/-- operators for non-primitive types.

assigned to @christos

This merge request affects 4 packages:

• PhysicsAnalysis/DerivationFramework/DerivationFrameworkBPhys
• PhysicsAnalysis/DerivationFramework/DerivationFrameworkExotics
• PhysicsAnalysis/DerivationFramework/DerivationFrameworkInDet
• PhysicsAnalysis/DerivationFramework/DerivationFrameworkMCTruth

Affected files list will not be printed in this case

Adding @zmarshal ,@jcatmore ,@dshope ,@stsuno ,@lshan ,@wwalko ,@battagl ,@abarton as watchers

added Derivation master review-pending-level-1 labels

The system determined that CI tests (with names matching "^CITest_SimulationRun(2|3)AF3.*$") are not needed for this code change. They are not run. This is not an indicator to restart the job.

CI Result SUCCESS (hash 9d99a759)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis	DetCommon
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
DetCommon: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 57934]

removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit 49890240

added sweep:ignore label