Move seg_to to a new header, define SkSegType enum there

include/core/SkPathMeasure.h

Index: include/core/SkPathMeasure.h
diff --git a/include/core/SkPathMeasure.h b/include/core/SkPathMeasure.h
index 2a512b8c382cbdd09990b92d4facf4fad90c9448..1044f7eeb06960d932ac9620b93ce59fd5f9d813 100644
--- a/include/core/SkPathMeasure.h
+++ b/include/core/SkPathMeasure.h
@@ -95,7 +95,8 @@ private:
         SkScalar    fDistance;  // total distance up to this point
         unsigned    fPtIndex; // index into the fPts array
         unsigned    fTValue : 30;
-        unsigned    fType : 2;
+        unsigned    fType : 2;  // actually the enum SkSegType
+                                // See SkPathMeasurePriv.h
 
         SkScalar getScalarT() const;
     };