package/gnupg2: add readline optional dependency

This is to improve build reproducibility.

[Thomas: add --with-readline and --without-readline options to
explicitly enable/disable readline usage.]

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gnupg2/gnupg2.mk

@@ -33,4 +33,11 @@ else
 GNUPG2_CONF_OPT += --disable-bzip2
 endif
 
+ifeq ($(BR2_PACKAGE_READLINE),y)
+GNUPG2_CONF_OPT += --with-readline=$(STAGING_DIR)
+GNUPG2_DEPENDENCIES += readline
+else
+GNUPG2_CONF_OPT += --without-readline
+endif
+
 $(eval $(autotools-package))