Set VERSION also when the source directory is a git submodule using a ".git" file pointing to the repo. directory.
diff --git a/configure.ac b/configure.ac
index 9c365ed..ede5f70 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1029,8 +1029,8 @@
dnl jemalloc configuration.
dnl
-dnl Set VERSION if source directory has an embedded git repository.
-if test -d "${srcroot}.git" ; then
+dnl Set VERSION if source directory has an embedded git repository or is a git submodule.
+if test -e "${srcroot}.git" ; then
git describe --long --abbrev=40 > ${srcroot}VERSION
fi
jemalloc_version=`cat ${srcroot}VERSION`