package/gnutls: add host support for pkcs11

Future U-Boot 2026.07 will build mkeficapsule with pkcs11 support. [1]

This causes link errors with Buildroot, such as the following one:

   mkeficapsule.c:(.text.startup+0xcd3): undefined reference to `gnutls_pkcs11_init'

(Other symbols the linker complains about are: gnutls_pkcs11_add_provider,
gnutls_pkcs11_obj_list_import_url4, gnutls_x509_crt_import_pkcs11 and
gnutls_pkcs11_deinit.)

The following example commands can be used to reproduce the issue:

     make qemu_aarch64_ebbr_defconfig
     echo 'BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2026.07-rc3"' >>.config
     echo 'BR2_TARGET_UBOOT_NEEDS_GNUTLS=y' >>.config
     echo '# BR2_DOWNLOAD_FORCE_CHECK_HASHES is not set' >>.config
     make olddefconfig
     make uboot

This commit adds the pkcs11 support for host-gnutls.

In Buildroot, since host-gnutls is currently only needed by uboot
(and other uboot derivatives such as uboot-tools) the pkcs11 support
is added unconditionally to host-gnutls.

Link: 0c716a157b [1]
Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>
Signed-off-by: Fiona Klute <fiona.klute@gmx.de>

package/gnutls/gnutls.mk

@@ -43,7 +43,8 @@ GNUTLS_CONF_ENV = gl_cv_socket_ipv6=yes \
 	gl_cv_func_gettimeofday_clobber=no
 GNUTLS_INSTALL_STAGING = YES
 
-HOST_GNUTLS_DEPENDENCIES = host-pkgconf host-libtasn1 host-libunistring host-nettle
+HOST_GNUTLS_DEPENDENCIES = host-pkgconf host-libtasn1 host-libunistring \
+	host-nettle host-p11-kit
 HOST_GNUTLS_CONF_OPTS = \
 	--disable-doc \
 	--disable-libdane \
@@ -64,7 +65,7 @@ HOST_GNUTLS_CONF_OPTS = \
 	--disable-openssl-compatibility \
 	--without-brotli \
 	--without-idn \
-	--without-p11-kit \
+	--with-p11-kit \
 	--without-zlib \
 	--without-zstd