MuonTrackPerformance: Fix clang warnings.

clang warnings: missing override keywords.

This merge request affects 1 package:

• MuonSpectrometer/MuonValidation/MuonRecValidation/MuonTrackPerformance

Adding @rosati ,@wleight as watchers

added MuonSpectrometer master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-20180-2019-01-05-01-30
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST 31938] (for remote access see the FAQ for MR reviewers)

The changes look ok. Adding review-approved label.

L1 shifter

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit f86e7f7d

added sweep:ignore label