package/flutter-gallery: clean up install_target_cmds

Remove and create the kernel_blob.bin file in the flutter_assets directory:

  When Flutter compiles the source code, it creates the kernel_blob.bin file,
  a Dart Kernel Bytecode of the application.

  If kernel_blob.bin exists inside the flutter_assets directory, then the
  application source code can be extracted with nothing more than apktool.
  Not only is this a security risk, it's also redundant and a waste of space.

  Removing the kernel_blob.bin file generated for flutter-gallery saves 86M!
  Because this package is a reference package, and some applications may check
  if the kernel_blob.bin file exists, we also touch a blank kernel_blob.bin
  file.

Do not use relative symlinks:
  Users may install their applications in any arbitaryt location, not
  necessarily in the /usr/share/flutter/${package_name} directory. Because
  flutter-gallery is a reference application, using exact symlinks to
  icudtl.dat and libflutter_engine.so is preferable.

Signed-off-by: Adam Duskett <adam.duskett@amarulasolutions.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/flutter-gallery/flutter-gallery.mk

@@ -46,10 +46,12 @@ define FLUTTER_GALLERY_INSTALL_TARGET_CMDS
 	$(INSTALL) -D -m 0755 $(@D)/libapp.so \
 		$(FLUTTER_GALLERY_INSTALL_DIR)/lib/libapp.so
 
-	ln -sf ../../../$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat \
+	ln -sf /usr/share/flutter/$(FLUTTER_ENGINE_RUNTIME_MODE)/data/icudtl.dat \
 	$(FLUTTER_GALLERY_INSTALL_DIR)/data/
 
-	ln -sf ../../../../../lib/libflutter_engine.so $(FLUTTER_GALLERY_INSTALL_DIR)/lib/
+	ln -sf /usr/lib/libflutter_engine.so $(FLUTTER_GALLERY_INSTALL_DIR)/lib/
+	$(RM) $(FLUTTER_GALLERY_INSTALL_DIR)/data/flutter_assets/kernel_blob.bin
+	touch $(FLUTTER_GALLERY_INSTALL_DIR)/data/flutter_assets/kernel_blob.bin
 endef
 
 $(eval $(generic-package))