Remove PI definition from Direct2D wxGraphicsContext code.

The line defining PI didn't compile with VC10 because atan(1) is ambiguous
(argument could be float, double or long double). And it was not needed anyhow
as PI was not used anywhere (and if it were, we should be just using M_PI from
wx/math.h anyhow), so simply remove it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77665 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/graphicsd2d.cpp

@@ -1160,7 +1160,6 @@ void wxD2DPathData::AddCurveToPoint(wxDouble cx1, wxDouble cy1, wxDouble cx2, wx
 // adds an arc of a circle centering at (x,y) with radius (r) from startAngle to endAngle
 void wxD2DPathData::AddArc(wxDouble x, wxDouble y, wxDouble r, wxDouble startAngle, wxDouble endAngle, bool clockwise)
 {
-    static wxDouble PI = std::atan(1) * 4;
     wxPoint2DDouble center = wxPoint2DDouble(x, y);
     wxPoint2DDouble start = wxPoint2DDouble(std::cos(startAngle) * r, std::sin(startAngle) * r);
     wxPoint2DDouble end = wxPoint2DDouble(std::cos(endAngle) * r, std::sin(endAngle) * r);