package/tvheadend: add support for host-python3

Added upstream:
https://github.com/tvheadend/tvheadend/commit/5a07ff166a84c65f08d326c69c818f6eef315e68

Tested with these defconfigs:

BR2_TOOLCHAIN_BUILDROOT_LARGEFILE=y
BR2_TOOLCHAIN_BUILDROOT_INET_IPV6=y
BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
BR2_PACKAGE_PYTHON3=y
BR2_PACKAGE_TVHEADEND=y

BR2_TOOLCHAIN_BUILDROOT_LARGEFILE=y
BR2_TOOLCHAIN_BUILDROOT_INET_IPV6=y
BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
BR2_PACKAGE_PYTHON=y
BR2_PACKAGE_TVHEADEND=y

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

package/tvheadend/tvheadend.mk

@@ -8,7 +8,7 @@ TVHEADEND_VERSION = fcd16fa0d835d7fd4f57c350ed8b76350440c68c
 TVHEADEND_SITE = $(call github,tvheadend,tvheadend,$(TVHEADEND_VERSION))
 TVHEADEND_LICENSE = GPLv3+
 TVHEADEND_LICENSE_FILES = LICENSE.md
-TVHEADEND_DEPENDENCIES = host-pkgconf host-python openssl
+TVHEADEND_DEPENDENCIES = host-pkgconf $(if $(BR2_PACKAGE_PYTHON3),host-python3,host-python) openssl
 
 ifeq ($(BR2_PACKAGE_AVAHI),y)
 TVHEADEND_DEPENDENCIES += avahi
@@ -42,7 +42,7 @@ define TVHEADEND_CONFIGURE_CMDS
 	 --prefix=/usr				\
 	 --arch="$(ARCH)"			\
 	 --cpu="$(BR2_GCC_TARGET_CPU)"		\
-	 --python="$(HOST_DIR)/usr/bin/python2"	\
+	 --python="$(HOST_DIR)/usr/bin/python"	\
 	 --disable-dvbscan			\
 	 --enable-bundle			\
 	 --disable-libffmpeg_static		\