Add deprecation message for Autotools

Author: Youw

BUILD.autotools.md

@@ -1,4 +1,12 @@
-# Building HIDAPI using Autotools
+# Building HIDAPI using Autotools (deprecated)
+
+---
+**NOTE**: for all intentions and purposes the Autotools build scripts for HIDAPI are _deprecated_ and going to be obsolete in the future.
+HIDAPI Team recommends using CMake build for HIDAPI.
+If you are already using Autotools build scripts provided by HIDAPI,
+consider switching to CMake build scripts as soon as possible.
+
+---
 
 To be able to use Autotools to build HIDAPI, it has to be [installed](#installing-autotools)/available in the system.
 

BUILD.md

@@ -17,12 +17,14 @@
 For various reasons you may need to build HIDAPI on your own.
 
 It can be done in several different ways:
-- using [Autotools](BUILD.autotools.md);
 - using [CMake](BUILD.cmake.md);
+- using [Autotools](BUILD.autotools.md) (deprecated);
 - using [manual makefiles](#building-the-manual-way-on-unix-platforms).
 
 **Autotools** build system is historically first mature build system for
-HIDAPI. Most common usage of it is in its separate README: [BUILD.autotools.md](BUILD.autotools.md).
+HIDAPI. Most common usage of it is in its separate README: [BUILD.autotools.md](BUILD.autotools.md).<br/>
+NOTE: for all intentions and purposes the Autotools build scripts for HIDAPI are _deprecated_ and going to be obsolete in the future.
+HIDAPI Team recommends using CMake build for HIDAPI.
 
 **CMake** build system is de facto an industry standard for many open-source and proprietary projects and solutions.
 HIDAPI is one of the projects which uses the power of CMake for its advantage.

configure.ac

@@ -2,6 +2,9 @@ AC_PREREQ(2.63)
 
 AC_INIT([hidapi],[m4_normalize(m4_builtin([include], VERSION))],[https://github.com/libusb/hidapi/issues])
 
+echo "This build script for HIDAPI is deprecated."
+echo "Consider using CMake instead."
+
 # Library soname version
 # Follow the following rules (particularly the ones in the second link):
 #  http://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html