revert libpng gdk_pixbuf_loader cmd (#5566)

packages/gdk_pixbuf.rb

@@ -25,9 +25,9 @@ class Gdk_pixbuf < Package
   depends_on 'glib'
   depends_on 'gobject_introspection' => :build
   depends_on 'jasper' => :build
-  depends_on 'libjpeg' => :build #Actually runtime
-  depends_on 'libpng' => :build #Actually runtime
-  depends_on 'libtiff' => :build #Actually runtime
+  depends_on 'libjpeg'
+  depends_on 'libpng'
+  depends_on 'libtiff'
   depends_on 'libwebp' => :build
   depends_on 'pango' => :build
   depends_on 'six' => :build
@@ -53,9 +53,9 @@ class Gdk_pixbuf < Package
   end
 
   def self.postinstall
-    ENV['GDK_PIXBUF_MODULEDIR'] = "#{CREW_LIB_PREFIX}/gdk-pixbuf-2.0/2.10.0/loaders"
-    ENV['GDK_PIXBUF_MODULE_FILE'] = "#{ENV['GDK_PIXBUF_MODULEDIR']}.cache"
-    system 'gdk-pixbuf-query-loaders --update-cache'
+    system 'env GDK_PIXBUF_MODULEDIR=#{CREW_LIB_PREFIX}/gdk-pixbuf-2.0/2.10.0/loaders \
+      GDK_PIXBUF_MODULE_FILE=#{CREW_LIB_PREFIX}/gdk-pixbuf-2.0/2.10.0/loaders.cache \
+      gdk-pixbuf-query-loaders --update-cache'
     gdk_pixbuf_in_bashrc = `grep -c "GDK_PIXBUF_MODULEDIR" ~/.bashrc || true`
     unless gdk_pixbuf_in_bashrc.to_i.positive?
       puts 'Putting GDK_PIXBUF code in ~/.bashrc'.lightblue

packages/libpng.rb

@@ -45,11 +45,6 @@ class Libpng < Package
   end
 
   def self.postinstall
-    # *.png: Unrecognized image file format (gdk-pixbuf-error-quark, 3)
     system 'update-mime-database', "#{CREW_PREFIX}/share/mime"
-    if File.exist?("#{CREW_PREFIX}/bin/gdk-pixbuf-query-loaders")
-      system 'gdk-pixbuf-query-loaders',
-             '--update-cache'
-    end
   end
 end

packages/librsvg.rb

@@ -66,7 +66,8 @@ class Librsvg < Package
   end
 
   def self.postinstall
-    # gdk_pixbuf should be setting the correct env variables
-    system 'gdk-pixbuf-query-loaders'
-  end
+    if File.exist?("#{CREW_PREFIX}/bin/gdk-pixbuf-query-loaders")
+      system 'gdk-pixbuf-query-loaders',
+             '--update-cache'
+    end
 end