Allow build without git

gen_version_header.sh

@@ -4,7 +4,12 @@ if [[ -z $1 ]]; then
 	exit -1;
 fi
 
-ver=`git describe --tags --always --dirty`
+if [[ "$2" == "dummy" ]]; then
+	ver="v0.0.0-undefined"
+else
+	ver=`git describe --tags --always --dirty`
+fi
+
 echo "#ifndef _VERSION_GENERATED_H_" > $1
 echo "#define _VERSION_GENERATED_H_" >> $1
 echo "#define GIT_VERSION_STRING \"$ver\"" >> $1