title: MinGW GCC Toolchain missing from Eclispe CDT when using "Convert to a C/C++ Project"
body: <p>I'm having an issue when I try to convert an existing project in Eclipse Mars using File -> New -> Other -> C/C++ -> Convert to a C/C++ Project (Adds C/C++ Nature).  The MinGW GCC toolchain is not present.</p>
  
  <p>My project shows under "Candidates for conversion" but when I select "Makefile project" for Project Type and I uncheck :Show Project types and toolchains only if they are supported on the platform" my only option for toolchains is "GNU Autotools Toolchain."</p>
  
  <p>I've made sure the MinGW install is set in my path variable as well as MINGW_HOME.</p>
  
  <p>However, if I create a new C++ project the MinGW GCC toolchain is present and I'm able to create the a new project. </p>
  
  <p>Eclipse Info: 
  Version: Mars.1 Release (4.5.1)
  Build id: 20150924-1200</p>