package/samba4: add optional dependency to libunwind

Upstream added configure options for libunwind in commit
https://github.com/samba-team/samba/commit/14feb93d481011765f62614ab49b304e17e4f6fd

Fixes:
http://autobuild.buildroot.net/results/63c/63c469106e9daa198f77d8da7a5bb123edcce0f7/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit bca9d7e58a23fc8c4a27be7971ace1fc84526d22)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/samba4/samba4.mk

@@ -93,6 +93,13 @@ else
 SAMBA4_CONF_OPTS += --without-libarchive
 endif
 
+ifeq ($(BR2_PACKAGE_LIBUNWIND),y)
+SAMBA4_CONF_OPTS += --with-libunwind
+SAMBA4_DEPENDENCIES += libunwind
+else
+SAMBA4_CONF_OPTS += --without-libunwind
+endif
+
 ifeq ($(BR2_PACKAGE_NCURSES),y)
 SAMBA4_CONF_ENV += NCURSES_CONFIG="$(STAGING_DIR)/usr/bin/$(NCURSES_CONFIG_SCRIPTS)"
 SAMBA4_DEPENDENCIES += ncurses