msmtp: add optional support for libgsasl

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/msmtp/msmtp.mk

@@ -10,11 +10,17 @@ MSMTP_SOURCE = msmtp-$(MSMTP_VERSION).tar.xz
 MSMTP_DEPENDENCIES = host-pkgconf
 MSMTP_CONF_OPTS = \
 	--without-libidn \
-	--disable-gai-idn \
-	--without-libgsasl
+	--disable-gai-idn
 MSMTP_LICENSE = GPL-3.0+
 MSMTP_LICENSE_FILES = COPYING
 
+ifeq ($(BR2_PACKAGE_LIBGSASL),y)
+MSMTP_CONF_OPTS += --with-libgsasl
+MSMTP_DEPENDENCIES += libgsasl
+else
+MSMTP_CONF_OPTS += --without-libgsasl
+endif
+
 ifeq ($(BR2_PACKAGE_LIBSECRET),y)
 MSMTP_CONF_OPTS += --with-libsecret
 MSMTP_DEPENDENCIES += libsecret