Exclude MathUtils from sip bindings

We don't want these part of stable API - this namespace really shouldn't
exist, as it mostly contains code which is duplicated in other
parts of the API (with better maintained and tested versions).

python/analysis/analysis_auto.sip

@@ -45,4 +45,3 @@
 %Include vector/qgsgeometrysnapper.sip
 %Include network/qgsgraphdirector.sip
 %Include network/qgsvectorlayerdirector.sip
-%Include interpolation/MathUtils.sip

src/analysis/interpolation/MathUtils.h

@@ -23,6 +23,8 @@
 class QgsPoint;
 class Vector3D;
 
+#define SIP_NO_FILE
+
 namespace MathUtils
 {
   //! Calculates the barycentric coordinates of a point (x,y) with respect to p1, p2, p3 and stores the three barycentric coordinates in 'result'. Thus the u-coordinate is stored in result::x, the v-coordinate in result::y and the w-coordinate in result::z. Attention: p1, p2 and p3 have to be ordered counterclockwise