title: CMake finding 32bit GDI+ on 64 bit platform
body: <p>I want to build a program that requires GDI+ on both 32-bit and 64-bit windows.
  I am using CMake 3.3.2, Windows 10 64-bit, Visual Studio 2015.
  As a minimal case I have this CMakeLists.txt:</p>
  
  <pre><code>cmake_minimum_required(VERSION 3.3)
  find_library(GDIP gdiplus)
  </code></pre>
  
  <p>I run this in the build sub-directory as</p>
  
  <pre><code>cmake ..
  </code></pre>
  
  <p>or</p>
  
  <pre><code>cmake -A x64 ..
  </code></pre>
  
  <p>If I compare the CMakeCache.txt for both runs I see it definitely has picked 32 or 64 bit options (e.g. for <code>CMAKE_LINKER</code>) but it has found the 32-bit <code>gdiplus.lib</code> in both cases</p>
  
  <pre><code>//Path to a library.
  GDIP:FILEPATH=C:/Program Files (x86)/Windows Kits/8.1/Lib/winv6.3/um/x86/gdiplus.lib
  </code></pre>
  
  <p>It should find the 64 bit version <code>C:/Program Files (x86)/Windows Kits/8.1/Lib/winv6.3/um/x64/gdiplus.lib</code> instead.</p>
  
  <p>Is there a way to get this right?</p>