configure: use exit 0 instead of just exit

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/configure b/configure
index 1ab2c7a..27cfb4d 100755
--- a/configure
+++ b/configure
@@ -117,7 +117,7 @@
   echo "CONFIG_POSIX_FALLOCATE=y"  >> $config_host_mak
   echo "CONFIG_FADVISE=y"          >> $config_host_mak
   echo "CONFIG_SFAA=y"             >> $config_host_mak
-  exit
+  exit 0
 elif check_define __OpenBSD__ ; then
   targetos='OpenBSD'
 elif check_define __sun__ ; then