0026852: Coding - compiler warnings issued by GCC 5.2.1

Compiler warnings eliminated:
- BRepAlgo_DSAccess: avoid copying of local list
- IntPatch, IntTools: initialize "possibly used uninitialized" variables by zeros
- Intf: slight refactoring
- OSD_signal: suppress unused argument
- OpenGL: add missing initializers in structures
- STEPConstruct_GDTProperty: correct function signature to pass output parameters by reference

src/IntTools/IntTools_EdgeEdge.cxx

@@ -1030,6 +1030,7 @@ Standard_Integer FindDistPC(const Standard_Real aT1A,
   //
   iC = bMaxDist ? 1 : -1;
   iErr = 0;
+  aT1max = aT2max = 0.; // silence GCC warning
   //
   aGS = 0.6180339887498948482045868343656;// =0.5*(1.+sqrt(5.))-1.;
   aA = aT1A;