Fix support Visual Studio 2015.

src/libs/vgeometry/vabstractcurve.cpp

@@ -40,6 +40,10 @@
 #include "../vmisc/compatibility.h"
 #include "../ifc/exception/vexceptionobjecterror.h"
 
+#if defined(Q_CC_MSVC) && _MSC_VER > 1900
+const qreal VAbstractCurve::minLength = ToPixel(1, Unit::Mm);
+#endif
+
 VAbstractCurve::VAbstractCurve(const GOType &type, const quint32 &idObject, const Draw &mode)
     :VGObject(type, idObject, mode), d (new VAbstractCurveData())
 {}

src/libs/vgeometry/vabstractcurve.h

@@ -112,7 +112,11 @@ public:
 
     void SetAliasSuffix(const QString &aliasSuffix) override;
 
+#if defined(Q_CC_MSVC) && _MSC_VER > 1900
+    static const qreal minLength;
+#else
     static constexpr qreal minLength = ToPixel(1, Unit::Mm);
+#endif
 protected:
     virtual void CreateName() =0;
     virtual void CreateAlias() =0;