tools: update configure

Fixes: e181db8ba4e0 ("m4: use test instead of []")
Signed-off-by: Wei Liu <wl@xen.org>

diff --git a/tools/configure b/tools/configure
index 35036dc1db6f1516ef50532ca767c7f3f012235d..3df1a01ff9d22d5df47c1a61e9f858cbace62289 100755 (executable)
--- a/tools/configure
+++ b/tools/configure
@@ -4688,7 +4688,7 @@ for ldflag in $APPEND_LIB
 do
     APPEND_LDFLAGS="$APPEND_LDFLAGS -L$ldflag"
 done
-if  ! -z $EXTRA_PREFIX ; then
+if test ! -z "$EXTRA_PREFIX" ; then
     CPPFLAGS="$CPPFLAGS -I$EXTRA_PREFIX/include"
     LDFLAGS="$LDFLAGS -L$EXTRA_PREFIX/lib"
 fi