build: support for Linux 3.7 UAPI

In Linux 3.7, nfnetlink.h moved below include/uapi/. Make configure
recognize that. Furthermore, we can drop the unnecessary indirection
via backticks and just ask grep directly if there was any result.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

diff --git a/configure.ac b/configure.ac
index 7a6aa3332cb48d58e5be0fdb3a57d24056e364a0..dea392dc6b5dca1c25494bb390a4302604e71394 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -68,7 +68,8 @@ fi
 
 AC_PROG_GREP
 
-if test "X`$GREP 'NFNL_SUBSYS_IPSET' $ksourcedir/include/linux/netfilter/nfnetlink.h`" = "X"
+if ! $GREP -q "NFNL_SUBSYS_IPSET" "$ksourcedir/include/linux/netfilter/nfnetlink.h" && \
+   ! $GREP -q "NFNL_SUBSYS_IPSET" "$ksourcedir/include/uapi/linux/netfilter/nfnetlink.h";
 then
        AC_MSG_ERROR([The kernel source directory $ksourcedir is not patched with netlink.patch to support ipset])
 fi