InDetServMatGeoModel: Fix cppcheck warnings.

• Pass class instances by const reference, not by value.
• Prefer preincrement to postincrement for iterators.

This merge request affects 1 package:

• InnerDetector/InDetDetDescr/InDetServMatGeoModel

Adding @goetz ,@sroe as watchers

added InnerDetector master review-pending-level-1 labels

CI Result SUCCESS (hash c60fbf39)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
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
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 21103]

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

merged

mentioned in commit 105ad0ad

added sweep:ignore label