doxygen: add newline after \file

While \file doesn't need an argument, it can't have another doxy
command after it.

source/blender/blenlib/BLI_scanfill.h

@@ -20,7 +20,8 @@
 #ifndef __BLI_SCANFILL_H__
 #define __BLI_SCANFILL_H__
 
-/** \file \ingroup bli
+/** \file
+ * \ingroup bli
  */
 
 struct ScanFillVert;