Use one common file for the version number in both build systems

CMakeLists.txt

@@ -6,7 +6,11 @@ SET(CMAKE_VERBOSE_MAKEFILE ON)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
 # N2n release information
-set(N2N_VERSION "3.1.0")
+execute_process(
+        COMMAND cat VERSION
+        WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+        OUTPUT_VARIABLE N2N_VERSION
+)
 set(N2N_OSNAME ${CMAKE_SYSTEM_NAME})
 execute_process(
         COMMAND git status

VERSION

@@ -0,0 +1 @@
+3.1.0

autogen.sh

@@ -1,11 +1,6 @@
 #!/usr/bin/env bash
 
-# NOTE: update version in CMakeLists.txt after changing these
-N2N_MAJOR="3"
-N2N_MINOR="1"
-N2N_PATCH="0"
-
-N2N_VERSION_SHORT="$N2N_MAJOR.$N2N_MINOR.$N2N_PATCH"
+N2N_VERSION_SHORT=$(cat VERSION)
 
 cat configure.seed | sed \
     -e "s/@N2N_VERSION_SHORT@/$N2N_VERSION_SHORT/g" \