Fix for spurious assert in cv::compareHist

When comparing histograms that look like multi-channel images (e.g a 3D histogram, of 4x4x4 bins, might appear as a CV_32FC4 matrix), cv::compareHist would complain because it was expecting the matrix type() == CV_32F. Now we test matrix depth() == CV_32F instead.

modules/imgproc/src/histogram.cpp

@@ -1970,7 +1970,7 @@ double cv::compareHist( InputArray _H1, InputArray _H2, int method )
     double result = 0;
     int j, len = (int)it.size;
 
-    CV_Assert( H1.type() == H2.type() && H1.type() == CV_32F );
+    CV_Assert( H1.type() == H2.type() && H1.depth() == CV_32F );
 
     double s1 = 0, s2 = 0, s11 = 0, s12 = 0, s22 = 0;