ccstruct/ocrblock.cpp: Fix compiler warnings

Compiler warnings from clang:

src/ccstruct/ocrblock.cpp:74:12: warning:
 use of old-style cast [-Wold-style-cast]
src/ccstruct/ocrblock.cpp:74:21: warning:
 cast from 'const void *' to 'ROW **' drops const qualifier [-Wcast-qual]
src/ccstruct/ocrblock.cpp:75:16: warning:
 cast from 'const void *' to 'ROW **' drops const qualifier [-Wcast-qual]
src/ccstruct/ocrblock.cpp:75:7: warning:
 use of old-style cast [-Wold-style-cast]

Make also the function decreasing_top_order a local function as it is
only used locally and remove its global declarations (2 locations).

Signed-off-by: Stefan Weil <sw@weilnetz.de>

src/ccstruct/ocrblock.cpp

@@ -68,11 +68,9 @@ BLOCK::BLOCK(const char *name,                //< filename
  * Sort Comparator: Return <0 if row1 top < row2 top
  */
 
-int decreasing_top_order(  //
-                         const void *row1,
-                         const void *row2) {
-  return (*(ROW **) row2)->bounding_box ().top () -
-    (*(ROW **) row1)->bounding_box ().top ();
+static int decreasing_top_order(const void *row1, const void *row2) {
+  return (*reinterpret_cast<ROW* const*>(row2))->bounding_box().top() -
+    (*reinterpret_cast<ROW* const*>(row1))->bounding_box().top();
 }
 
 

src/ccstruct/ocrblock.h

@@ -211,8 +211,6 @@ class BLOCK:public ELIST_LINK
   ICOORD median_size_;         //< Median size of blobs.
 };
 
-int decreasing_top_order(const void *row1, const void *row2);
-
 // A function to print segmentation stats for the given block list.
 void PrintSegmentationStats(BLOCK_LIST* block_list);
 

src/ccstruct/pdblock.h

@@ -171,6 +171,4 @@ class DLLSYM BLOCK_LINE_IT
     BLOCK_RECT_IT rect_it;       //< rectangle iterator
 };
 
-int decreasing_top_order(const void *row1,
-                         const void *row2);
 #endif