[libvirt] [PATCH] build: restore support for libyajl 2.0.1

[Ján Tomko]

Commit 105756660f944e7db02de3b55b98bb7c11cd03bf was too eager and did
not consider SLE 12 which still has 2.0.1 that does not ship
a pkg-config file.

Similar to how we check for readline, prefer pkg-config if available
and fall back to the old detection code if not found.

NB: this is not a clean revert because we're not reintroducing support
for YAJL 1.

Signed-off-by: Ján Tomko <jtomko at redhat.com>
Reported-by: Olaf Hering <olaf at aepfle.de>
---
 m4/virt-yajl.m4 | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/m4/virt-yajl.m4 b/m4/virt-yajl.m4
index 494e722963..05a8f8b9bd 100644
--- a/m4/virt-yajl.m4
+++ b/m4/virt-yajl.m4
@@ -24,7 +24,19 @@ AC_DEFUN([LIBVIRT_ARG_YAJL],[
 AC_DEFUN([LIBVIRT_CHECK_YAJL],[
   dnl YAJL JSON library http://lloyd.github.com/yajl/
 
-  LIBVIRT_CHECK_PKG([YAJL], [yajl], [2.0.3])
+  PKG_CHECK_EXISTS([readline], [use_pkgconfig=1], [use_pkgconfig=0])
+
+  if test $use_pkgconfig = 1; then
+    dnl 2.0.3 was the version where the pkg-config file was first added
+    LIBVIRT_CHECK_PKG([YAJL], [yajl], [2.0.3])
+  else
+    dnl SUSE SLE 12 and OpenSUSE Leap 42.3 still use 2.0.1
+    dnl TODO: delete this in July 2020
+    LIBVIRT_CHECK_LIB_ALT([YAJL], [yajl],
+                          [yajl_tree_parse], [yajl/yajl_common.h])
+
+  fi
+
 ])
 
 AC_DEFUN([LIBVIRT_RESULT_YAJL],[
-- 
2.19.2