Remove DDK support files. (#333)

Deleted DDK build scripts, support files and documentation for it,
as it wasn't working of-the-box with recent tool-sets from MS anyway.

Still keeping `HIDAPI_USE_DDK` macro in the code,
as it still _can_ be used if the build configuration is setup properly.

Resolves: #49

Author: Youw

BUILD.md

@@ -106,19 +106,5 @@ To build HIDAPI using MinGW or Cygwin using Autotools, use a general Autotools
 
 Any windows builds (MSVC or MinGW/Cygwin) are also supported by [CMake](BUILD.cmake.md).
 
-HIDAPI can also be built using the Windows DDK (now also called the Windows
-Driver Kit or WDK). This method was originally required for the HIDAPI build
-but not anymore. However, some users still prefer this method. It is not as
-well supported anymore but should still work. Patches are welcome if it does
-not. To build using the DDK:
-
-   1. Install the Windows Driver Kit (WDK) from Microsoft.
-   2. From the Start menu, in the Windows Driver Kits folder, select Build
-      Environments, then your operating system, then the x86 Free Build
-      Environment (or one that is appropriate for your system).
-   3. From the console, change directory to the `windows/ddk_build/` directory,
-      which is part of the HIDAPI distribution.
-   4. Type build.
-   5. You can find the output files (DLL and LIB) in a subdirectory created
-      by the build system which is appropriate for your environment. On
-      Windows XP, this directory is `objfre_wxp_x86/i386`.
+If you are looking for information regarding DDK build of HIDAPI
+- the build has been broken for a while and now the support files are obsolete.

windows/Makefile.am

@@ -8,7 +8,6 @@ hdrdir = $(includedir)/hidapi
 hdr_HEADERS = $(top_srcdir)/hidapi/hidapi.h
 
 EXTRA_DIST = \
-  ddk_build \
   hidapi.vcproj \
   hidtest.vcproj \
   Makefile-manual \