Remove CI support for mingw32

The tests have never run successfully and we do have successful builds
of mingw-w64, so remove these CI builds which do not add value.

.travis.yml

@@ -37,9 +37,6 @@ matrix:
    - os: osx
      compiler: gcc
  include:
-   - compiler: i586-mingw32msvc-gcc
-     env: OPTIONS="-DCMAKE_TOOLCHAIN_FILE=../script/toolchain-mingw32.cmake" SKIP_TESTS=1
-     os: linux
    - compiler: gcc
      env: COVERITY=1
      os: linux

appveyor.yml

@@ -13,15 +13,9 @@ environment:
   - GENERATOR: "Visual Studio 11 Win64"
     ARCH: 64
   - GENERATOR: "MSYS Makefiles"
-    ARCH: 32
-  - GENERATOR: "MSYS Makefiles"
     ARCH: i686 # this is for 32-bit MinGW-w64
   - GENERATOR: "MSYS Makefiles"
     ARCH: 64
-matrix:
-  allow_failures:
-    - GENERATOR: "MSYS Makefiles"
-      ARCH: 32
 cache:
 - i686-4.9.2-release-win32-sjlj-rt_v3-rev1.7z
 - x86_64-4.9.2-release-win32-seh-rt_v3-rev1.7z

script/appveyor-mingw.sh

 #!/bin/sh
 set -e
 cd `dirname "$0"`/..
-if [ "$ARCH" = "32" ]; then
-  echo 'C:\MinGW\ /MinGW' > /etc/fstab
-elif [ "$ARCH" = "i686" ]; then
+if [ "$ARCH" = "i686" ]; then
   f=i686-4.9.2-release-win32-sjlj-rt_v3-rev1.7z
   if ! [ -e $f ]; then
     curl -LsSO http://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/4.9.2/threads-win32/sjlj/$f

script/toolchain-mingw32.cmake

-# CMake toolchain file for Win32 cross-compile
-SET(CMAKE_SYSTEM_NAME Windows)
-
-SET(CMAKE_C_COMPILER i586-mingw32msvc-gcc)
-SET(CMAKE_RC_COMPILER i586-mingw32msvc-windres)
-
-SET(CMAKE_FIND_ROOT_PATH /usr/i586-mingw32msvc)
-
-SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
-SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
-SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
-
-SET(ENV{PKG_CONFIG_LIBDIR} ${CMAKE_FIND_ROOT_PATH}/lib/pkgconfig)