optipng: fix libpng dependency

media-gfx/optipng/optipng-0.7.6.recipe

@@ -5,7 +5,7 @@ convert other image formats, such as BMP, GIF, PNM and TIFF, to PNG files."
 HOMEPAGE="http://optipng.sourceforge.net/"
 COPYRIGHT="2001-2016 Cosmin Truta"
 LICENSE="Zlib"
-REVISION="1"
+REVISION="2"
 SOURCE_URI="http://downloads.sf.net/optipng/optipng-$portVersion.tar.gz"
 CHECKSUM_SHA256="4870631fcbd3825605f00a168b8debf44ea1cda8ef98a73e5411eee97199be80"
 
@@ -17,21 +17,21 @@ PROVIDES="
 	"
 REQUIRES="
 	haiku
-	lib:libpng >= 16
+	lib:libpng16
 	lib:libz
 	"
 
 BUILD_REQUIRES="
-	haiku${secondaryArchSuffix}_devel
-	devel:libpng >= 16
+	haiku_devel
+	devel:libpng16
 	devel:libz
 	"
 BUILD_PREREQUIRES="
 	cmd:ar
+	cmd:diff
 	cmd:gcc
 	cmd:make
 	cmd:ranlib
-	cmd:diff
 	"
 
 BUILD()