Remove old msc ver. Freecad 0.20 require 64 bit and windows 7 or higher. For this reason, msc libraries less than 1800 will no longer be used. (#7036)

* remove msc<1800

src/Mod/Fem/App/FemConstraint.cpp

@@ -70,12 +70,7 @@
 
 using namespace Fem;
 
-// maybe in the c++ standard later, older compiler don't have round()
-#if _MSC_VER <= 1700
-double round(double r) {
-    return (r > 0.0) ? floor(r + 0.5) : ceil(r - 0.5);
-}
-#endif
+
 
 #if OCC_VERSION_HEX >= 0x070600
 using Adaptor3d_HSurface = Adaptor3d_Surface;