When checking for __sync_sub_and_fetch, don't underquote, to shut up recent autoconf

Without the correct number of levels of quoting, autoconf mistakenly
believes we didn't use AC_LANG_SOURCE where required. (In fact,
AC_LANG_PROGRAM calls AC_LANG_SOURCE.)

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=19681
Reviewed-by: Colin Walters <walters@verbum.org>

diff --git a/configure.ac b/configure.ac
index 6df79fd..7001a87 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -441,8 +441,8 @@ fi
 
 AC_CACHE_CHECK([whether $CC knows __sync_sub_and_fetch()],
   dbus_cv_sync_sub_and_fetch,
-  [AC_LINK_IFELSE(
-     AC_LANG_PROGRAM([], [[int a = 4; int b = __sync_sub_and_fetch(&a, 4); exit(b); ]]),
+  [AC_LINK_IFELSE([
+     AC_LANG_PROGRAM([[]], [[int a = 4; int b = __sync_sub_and_fetch(&a, 4); exit(b); ]])],
      [dbus_cv_sync_sub_and_fetch=yes],
      [dbus_cv_sync_sub_and_fetch=no])
   ])