Revert "build: add --with-jansson"

This reverts commit 12b34f09.

Jansson cannot parse QEMU's quirky JSON.
Revert back to yajl.

https://bugzilla.redhat.com/show_bug.cgi?id=1614569

Conflicts:
  configure.ac:
    Commit 8aa85e0b introduced LIBVIRT_*_LIBISCSI macros.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

configure.ac

@@ -250,7 +250,6 @@ LIBVIRT_ARG_FIREWALLD
 LIBVIRT_ARG_FUSE
 LIBVIRT_ARG_GLUSTER
 LIBVIRT_ARG_HAL
-LIBVIRT_ARG_JANSSON
 LIBVIRT_ARG_LIBISCSI
 LIBVIRT_ARG_LIBPCAP
 LIBVIRT_ARG_LIBSSH
@@ -292,7 +291,6 @@ LIBVIRT_CHECK_FUSE
 LIBVIRT_CHECK_GLUSTER
 LIBVIRT_CHECK_GNUTLS
 LIBVIRT_CHECK_HAL
-LIBVIRT_CHECK_JANSSON
 LIBVIRT_CHECK_LIBISCSI
 LIBVIRT_CHECK_LIBNL
 LIBVIRT_CHECK_LIBPARTED
@@ -978,7 +976,6 @@ LIBVIRT_RESULT_FUSE
 LIBVIRT_RESULT_GLUSTER
 LIBVIRT_RESULT_GNUTLS
 LIBVIRT_RESULT_HAL
-LIBVIRT_RESULT_JANSSON
 LIBVIRT_RESULT_LIBISCSI
 LIBVIRT_RESULT_LIBNL
 LIBVIRT_RESULT_LIBPCAP

m4/virt-jansson.m4

-dnl The jansson library
-dnl
-dnl This library is free software; you can redistribute it and/or
-dnl modify it under the terms of the GNU Lesser General Public
-dnl License as published by the Free Software Foundation; either
-dnl version 2.1 of the License, or (at your option) any later version.
-dnl
-dnl This library is distributed in the hope that it will be useful,
-dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
-dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-dnl Lesser General Public License for more details.
-dnl
-dnl You should have received a copy of the GNU Lesser General Public
-dnl License along with this library.  If not, see
-dnl <http://www.gnu.org/licenses/>.
-dnl
-
-AC_DEFUN([LIBVIRT_ARG_JANSSON],[
-  LIBVIRT_ARG_WITH_FEATURE([JANSSON], [jansson], [check])
-])
-
-AC_DEFUN([LIBVIRT_CHECK_JANSSON],[
-  dnl Jansson http://www.digip.org/jansson/
-  LIBVIRT_CHECK_PKG([JANSSON], [jansson], [2.5])
-])
-
-AC_DEFUN([LIBVIRT_RESULT_JANSSON],[
-  LIBVIRT_RESULT_LIB([JANSSON])
-])