convert B2VectorContinuity to scoped enum

Change-Id: Id7c16223f579fea1e1d64c0b77327be1b6d5c8d9
Reviewed-on: https://gerrit.libreoffice.org/22631Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>

include/basegfx/vector/b2enums.hxx

@@ -40,7 +40,7 @@ namespace basegfx
 
     /** Descriptor for the mathematical continuity of two 2D Vectors
     */
-    enum B2VectorContinuity
+    enum class B2VectorContinuity
     {
         /// none
         NONE = 0,