opkg: Add gnupg signature checking support.

[Thomas: add ac_cv_path_GPGME_CONFIG in the configure environment to
help opkg find libgpgme.]

Signed-off-by: Philipp Claves <claves@budelmann-elektronik.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/opkg/Config.in

@@ -11,3 +11,13 @@ config BR2_PACKAGE_OPKG
 
 	  http://code.google.com/p/opkg/
 
+if BR2_PACKAGE_OPKG
+
+config BR2_PACKAGE_OPKG_GPG_SIGN
+	bool "gnupg support"
+	select BR2_PACKAGE_LIBGPGME
+	help
+	  Enable opkg package signature checking support using
+	  gnupg/libgpgme.
+
+endif

package/opkg/opkg.mk

@@ -9,7 +9,7 @@ OPKG_SOURCE = opkg-$(OPKG_VERSION).tar.gz
 OPKG_SITE = http://opkg.googlecode.com/svn/trunk/
 OPKG_SITE_METHOD = svn
 OPKG_INSTALL_STAGING = YES
-OPKG_CONF_OPT = --disable-curl --disable-gpg
+OPKG_CONF_OPT = --disable-curl
 OPKG_AUTORECONF = YES
 # Uses PKG_CHECK_MODULES() in configure.ac
 OPKG_DEPENDENCIES = host-pkgconf
@@ -19,6 +19,14 @@ define OPKG_CREATE_LOCKDIR
 	mkdir -p $(TARGET_DIR)/usr/lib/opkg
 endef
 
+ifeq ($(BR2_PACKAGE_OPKG_GPG_SIGN),y)
+OPKG_CONF_OPT += --enable-gpg
+OPKG_CONF_ENV = ac_cv_path_GPGME_CONFIG=$(STAGING_DIR)/usr/bin/gpgme-config
+OPKG_DEPENDENCIES += libgpgme
+else
+OPKG_CONF_OPT += --disable-gpg
+endif
+
 OPKG_POST_INSTALL_TARGET_HOOKS += OPKG_CREATE_LOCKDIR
 
 $(eval $(autotools-package))