configure: Suppress messages from pkg_config probe for check

Suppress confusing messages from pkg_config when probing for
'check' by sending them to /dev/null as we do with other
similar probes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

configure

diff --git a/configure b/configure
index 850efc0..254b801 100755
--- a/configure
+++ b/configure
@@ -1828,7 +1828,7 @@
 #include <check.h>
 int main(void) { suite_create("qemu test"); return 0; }
 EOF
-  check_libs=`$pkg_config --libs check`
+  check_libs=`$pkg_config --libs check 2>/dev/null`
   if compile_prog "" $check_libs ; then
     check_utests=yes
     libs_tools="$check_libs $libs_tools"