jpeg: convert old-style hooks to new-style hooks

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/jpeg/jpeg.mk

@@ -29,8 +29,10 @@ JPEG_INSTALL_TARGET_OPT = DESTDIR=$(TARGET_DIR) install
 JPEG_LIBTOOL_PATCH = NO
 JPEG_CONF_OPT = --without-x --enable-shared --enable-static
 
-$(eval $(call AUTOTARGETS,package,jpeg))
-
-$(JPEG_HOOK_POST_INSTALL):
+define JPEG_REMOVE_USELESS_TOOLS
 	rm -f $(addprefix $(TARGET_DIR)/usr/bin/,cjpeg djpeg jpegtrans rdjpgcom wrjpgcom)
-	touch $@
+endef
+
+JPEG_POST_INSTALL_TARGET_HOOKS += JPEG_REMOVE_USELESS_TOOLS
+
+$(eval $(call AUTOTARGETS,package,jpeg))