package/tvheadend: reduce target binary size by using pngquant

Support was added by this commit:
https://github.com/tvheadend/tvheadend/commit/8bf3932539ceadb3bfc1c9453f11175f15aefad2

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/tvheadend/tvheadend.mk

@@ -11,6 +11,7 @@ TVHEADEND_LICENSE_FILES = LICENSE.md
 TVHEADEND_DEPENDENCIES = \
 	host-gettext \
 	host-pkgconf \
+	host-pngquant \
 	$(if $(BR2_PACKAGE_PYTHON3),host-python3,host-python) \
 	openssl
 
@@ -81,12 +82,19 @@ define TVHEADEND_CONFIGURE_CMDS
 			--python="$(HOST_DIR)/usr/bin/python"	\
 			--enable-dvbscan			\
 			--enable-bundle				\
+			--enable-pngquant			\
 			--disable-ffmpeg_static			\
 			--disable-hdhomerun_static		\
 			$(TVHEADEND_CONF_OPTS)			\
 	)
 endef
 
+define TVHEADEND_FIX_PNGQUANT_PATH
+	$(SED) "s%^pngquant_bin =.*%pngquant_bin = '$(HOST_DIR)/usr/bin/pngquant'%" \
+		$(@D)/support/mkbundle
+endef
+TVHEADEND_POST_CONFIGURE_HOOKS += TVHEADEND_FIX_PNGQUANT_PATH
+
 define TVHEADEND_BUILD_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D)
 endef