gnupg2: security bump to version 2.2.6

Fixes CVE-2018-9234: Unenforced configuration allows for apparently
valid certifications actually signed by signing subkeys.

Remove --disable-doc from configure options. We pass this options to all
autotools packages.

Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gnupg2/gnupg2.hash

@@ -1,6 +1,6 @@
-# From https://lists.gnupg.org/pipermail/gnupg-announce/2018q1/000420.html
-sha1 9dec110397e460b3950943e18f5873a4f277f216  gnupg-2.2.5.tar.bz2
+# From https://lists.gnupg.org/pipermail/gnupg-announce/2018q2/000421.html
+sha1 295298debcc2c12f02a2f2fdf04aecb6d6aae396  gnupg-2.2.6.tar.bz2
 # Calculated based on the hash above and signature
-# https://gnupg.org/ftp/gcrypt/gnupg/gnupg-2.2.5.tar.bz2.sig
-sha256 3fa189a32d4fb62147874eb1389047c267d9ba088f57ab521cb0df46f08aef57  gnupg-2.2.5.tar.bz2
+# https://gnupg.org/ftp/gcrypt/gnupg/gnupg-2.2.6.tar.bz2.sig
+sha256 e64d8c5fa2d05938a5080cb784a98ac21be0812f2a26f844b18f0d6a0e711984  gnupg-2.2.6.tar.bz2
 sha256 bc2d6664f6276fa0a72d57633b3ae68dc7dcb677b71018bf08c8e93e509f1357  COPYING

package/gnupg2/gnupg2.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GNUPG2_VERSION = 2.2.5
+GNUPG2_VERSION = 2.2.6
 GNUPG2_SOURCE = gnupg-$(GNUPG2_VERSION).tar.bz2
 GNUPG2_SITE = https://gnupg.org/ftp/gcrypt/gnupg
 GNUPG2_LICENSE = GPL-3.0+
@@ -13,7 +13,7 @@ GNUPG2_DEPENDENCIES = zlib libgpg-error libgcrypt libassuan libksba libnpth \
 	$(if $(BR2_PACKAGE_LIBICONV),libiconv) host-pkgconf
 
 GNUPG2_CONF_OPTS = \
-	--disable-rpath --disable-regex --disable-doc \
+	--disable-rpath --disable-regex \
 	--with-libgpg-error-prefix=$(STAGING_DIR)/usr \
 	--with-libgcrypt-prefix=$(STAGING_DIR)/usr \
 	--with-libassuan-prefix=$(STAGING_DIR)/usr \