coverity #13369

git-svn-id: http://root.cern.ch/svn/root/trunk@36021 27541ba8-7e3a-0410-8455-c3a389f83636

graf2d/graf/src/TGraphPolargram.cxx

@@ -657,7 +657,7 @@ void TGraphPolargram::PaintRadialDivisions(Bool_t drawaxis)
       Int_t ndivminor = 0;
 
       chopt[0] = 0;
-      strcat(chopt, "SDH");
+      strncat(chopt, "SDH", 3);
       if (fNdivRad < 0) strcat(chopt, "N");
       if(drawaxis){
       // Paint axis.