Fixed "Conditional jump or move depends on uninitialised value(s)" valgrind…

Fixed "Conditional jump or move depends on uninitialised value(s)" valgrind issue due to wrong pointer recalculation for zero level of pyramid.

modules/legacy/src/pyrsegmentation.cpp

@@ -130,8 +130,8 @@ static void icvMaxRoi1( _CvRect16u *max_rect, int x, int y );
                                        (float)fabs((a).green - (b).green),  \
                                        (float)fabs((a).blue - (b).blue))*/
 
-#define _CV_NEXT_BASE_C1(p,n) (_CvPyramid*)((char*)(p) + (n)*sizeof(_CvPyramidBase))
-#define _CV_NEXT_BASE_C3(p,n) (_CvPyramidC3*)((char*)(p) + (n)*sizeof(_CvPyramidBaseC3))
+#define _CV_NEXT_BASE_C1(p,n) ((_CvPyramid*)((char*)(p) + (n)*(ptrdiff_t)sizeof(_CvPyramidBase)))
+#define _CV_NEXT_BASE_C3(p,n) ((_CvPyramidC3*)((char*)(p) + (n)*(ptrdiff_t)sizeof(_CvPyramidBaseC3)))
 
 
 CV_INLINE float icvRGBDist_Max( const _CvRGBf& a, const _CvRGBf& b )
@@ -868,7 +868,7 @@ icvPyrSegmentation8uC3R( uchar * src_image, int src_step,
 
                     if( p_cur[size.width].a == 0 )
                     {
-                        p_cur[size.width].c = p_prev[(l != 0) - 1].c;
+                        p_cur[size.width].c = (l != 0) ? p_prev->c : _CV_NEXT_BASE_C3( p_prev, -1 )->c;
                     }
                     else
                     {