build: don't do a submodule update if not a git checkout

This can happen if it's just a tarball created from a git tree, but not
a checkout.

diff --git a/autogen.sh b/autogen.sh
index b3176842b7627034f999bca0ed8bed57305f8887..55ca446d71e074869820d9ae87ff9be2f85cf748 100755 (executable)
--- a/autogen.sh
+++ b/autogen.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-[ ! -e .gitmodules ] || {
+[ ! -e .gitmodules ] || [ ! -d .git ] || {
     echo "autogen.sh: updating git submodules"
     git submodule init
     git submodule update