configure.ac: Check for expat21 if expat is not found.

Fixes build error on CentOS 6.9.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102052
Fixes: 5c007203b73d ("configure.ac: drop manual detection of expat header/library")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>

diff --git a/configure.ac b/configure.ac
index 52645bb44ff64e3ab48c7c0c45c6009926db4d88..53d52f6d52f90588360c39e2308a4d330735e9fc 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1814,7 +1814,9 @@ if test "x$with_dri_drivers" = xno; then
 fi
 
 # Check for expat
-PKG_CHECK_MODULES([EXPAT], [expat])
+PKG_CHECK_MODULES([EXPAT], [expat],,
+    [PKG_CHECK_MODULES([EXPAT], [expat21])]
+)
 
 dnl If $with_dri_drivers is yes, drivers will be added through
 dnl platform checks. Set DEFINES and LIB_DEPS