Merge topic 'FindPNG-1.6'

96fa4a2 FindPNG: Add versioned library names for 1.6 (#14289)

Modules/FindPNG.cmake

@@ -38,7 +38,10 @@ if(ZLIB_FOUND)
   /usr/local/include/libpng             # OpenBSD
   )
 
-  set(PNG_NAMES ${PNG_NAMES} png libpng png15 libpng15 png15d libpng15d png14 libpng14 png14d libpng14d png12 libpng12 png12d libpng12d)
+  list(APPEND PNG_NAMES png libpng)
+  foreach(v 16 15 14 12)
+    list(APPEND PNG_NAMES png${v} libpng${v} png${v}d libpng${v}d)
+  endforeach()
   find_library(PNG_LIBRARY NAMES ${PNG_NAMES} )
 
   if (PNG_LIBRARY AND PNG_PNG_INCLUDE_DIR)