Ensure source compiles with pedantic C++ compiler
diff --git a/coders/histogram.c b/coders/histogram.c
index d5a4087..ffce554 100644
--- a/coders/histogram.c
+++ b/coders/histogram.c
@@ -375,10 +375,10 @@
(LocaleCompare(write_info->magick,"HISTOGRAM") == 0))
(void) FormatLocaleString(histogram_image->filename,MagickPathExtent,
"miff:%s",write_info->filename);
- histogram_image->blob=DetachBlob(histogram_image->blob);
+ histogram_image->blob=(BlobInfo *) DetachBlob(histogram_image->blob);
histogram_image->blob=CloneBlobInfo(image->blob);
status=WriteImage(write_info,histogram_image,exception);
- image->blob=DetachBlob(image->blob);
+ image->blob=(BlobInfo *) DetachBlob(image->blob);
image->blob=CloneBlobInfo(histogram_image->blob);
histogram_image=DestroyImage(histogram_image);
write_info=DestroyImageInfo(write_info);