Fix some const correctness in TrkVKalVrtFitter

Former-commit-id: 3afbaf070f3e86f48732bbc14200118c40397f0a

Tracking/TrkVertexFitter/TrkVKalVrtFitter/TrkVKalVrtFitter/ITrkVKalVrtFitter.h

@@ -113,7 +113,7 @@ namespace Trk{
       virtual void setVertexForConstraint(double,double,double)=0;
       virtual void setCovVrtForConstraint(double,double,double,
                                           double,double,double)=0;
-      virtual void setMassInputParticles( std::vector<double>& )=0;
+      virtual void setMassInputParticles( const std::vector<double>& )=0;
       virtual void setDefault() =0;
       virtual void setZeroCharge(int)=0;
 //

Tracking/TrkVertexFitter/TrkVKalVrtFitter/TrkVKalVrtFitter/TrkVKalVrtFitter.h

@@ -225,7 +225,7 @@ namespace Trk{
         void setCovVrtForConstraint(double,double,double,
                                   double,double,double);
 				  
-        void setMassInputParticles( std::vector<double>& );
+        void setMassInputParticles( const std::vector<double>& );
         void setMomCovCalc(int);
         void setDefault();
         void setZeroCharge(int);

Tracking/TrkVertexFitter/TrkVKalVrtFitter/src/SetFitOptions.cxx

@@ -217,7 +217,7 @@ namespace Trk{
      m_CovVrtForConstraint.push_back(ZZ);
   }			  
 
-  void TrkVKalVrtFitter::setMassInputParticles( std::vector<double>& mass)
+  void TrkVKalVrtFitter::setMassInputParticles( const std::vector<double>& mass)
   { m_MassInputParticles.clear();
     for(int i=0; i<(int)mass.size(); i++) m_MassInputParticles.push_back(fabs(mass[i]));
   }