Move Arch Linux's VENDOR check above Ubuntu's

If the lsb-release package is installed on an Arch Linux distribution,
the configure step will incorrectly detect the running distribution as
Ubuntu. This is a result of both distributions providing an
/etc/lsb-release file, and the Ubuntu VENDOR check being performed
first.

Since the Arch Linux test check's for a file more specific to the Arch
Linux distribution, moving Arch Linux's VENDOR check above Unbuntu's
check provides a quick and easy solution.

Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

config/zfs-build.m4

@@ -234,12 +234,12 @@ AC_DEFUN([ZFS_AC_DEFAULT_PACKAGE], [
 		VENDOR=sles ;
 	elif test -f /etc/slackware-version ; then
 		VENDOR=slackware ;
+	elif test -f /etc/arch-release ; then
+		VENDOR=arch ;
 	elif test -f /etc/lsb-release ; then
 		VENDOR=ubuntu ;
 	elif test -f /etc/lunar.release ; then
 		VENDOR=lunar ;
-	elif test -f /etc/arch-release ; then
-		VENDOR=arch ;
 	else
 		VENDOR= ;
 	fi

configure

@@ -11859,12 +11859,12 @@ $as_echo_n "checking linux distribution... " >&6; }
 		VENDOR=sles ;
 	elif test -f /etc/slackware-version ; then
 		VENDOR=slackware ;
+	elif test -f /etc/arch-release ; then
+		VENDOR=arch ;
 	elif test -f /etc/lsb-release ; then
 		VENDOR=ubuntu ;
 	elif test -f /etc/lunar.release ; then
 		VENDOR=lunar ;
-	elif test -f /etc/arch-release ; then
-		VENDOR=arch ;
 	else
 		VENDOR= ;
 	fi