THRIFT-4081: appveyor retooling - added mingw64 build as a second job to the CI build process

This closes #1205
diff --git a/build/appveyor/cl_showenv.bat b/build/appveyor/cl_showenv.bat
new file mode 100644
index 0000000..33dd660
--- /dev/null
+++ b/build/appveyor/cl_showenv.bat
@@ -0,0 +1,67 @@
+::
+:: Licensed under the Apache License, Version 2.0 (the "License");
+:: you may not use this file except in compliance with the License.
+:: You may obtain a copy of the License at
+::
+::     http://www.apache.org/licenses/LICENSE-2.0
+::
+:: Unless required by applicable law or agreed to in writing, software
+:: distributed under the License is distributed on an "AS IS" BASIS,
+:: WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+:: See the License for the specific language governing permissions and
+:: limitations under the License.
+::
+
+ECHO/
+ECHO ===============================================================================
+IF "%PROFILE:~0,4%" == "MSVC" (
+ECHO Versions
+ECHO -------------------------------------------------------------------------------
+ECHO boost                 = %BOOST_VERSION%
+ECHO libevent              = %LIBEVENT_VERSION%
+ECHO python                = %PYTHON_VERSION%
+ECHO qt                    = %QT_VERSION%
+ECHO zlib                  = %ZLIB_VERSION%
+ECHO/
+)
+ECHO Appveyor Variables
+ECHO -------------------------------------------------------------------------------
+ECHO APPVEYOR_BUILD_FOLDER = %APPVEYOR_BUILD_FOLDER%
+ECHO CONFIGURATION         = %CONFIGURATION%
+ECHO PLATFORM              = %PLATFORM%
+ECHO PROFILE               = %PROFILE%
+ECHO/
+ECHO Our Variables
+ECHO -------------------------------------------------------------------------------
+ECHO APPVEYOR_SCRIPTS      = %APPVEYOR_SCRIPTS%
+ECHO BOOST_ROOT            = %BOOST_ROOT%
+ECHO BOOST_INCLUDEDIR      = %BOOST_INCLUDEDIR%
+ECHO BOOST_LIBRARYDIR      = %BOOST_LIBRARYDIR%
+ECHO BUILDCACHE            = %BUILDCACHE%
+ECHO BUILDDIR              = %BUILDDIR%
+ECHO COMPILER              = %COMPILER%
+ECHO GENERATOR             = %GENERATOR%
+ECHO INSTDIR               = %INSTDIR%
+ECHO JAVA_HOME             = %JAVA_HOME%
+ECHO OPENSSL_ROOT          = %OPENSSL_ROOT%
+ECHO SRCDIR                = %SRCDIR%
+ECHO WIN3P                 = %WIN3P%
+ECHO WITH_PYTHON           = %WITH_PYTHON%
+ECHO ZLIB_STATIC_SUFFIX    = %ZLIB_STATIC_SUFFIX%
+IF NOT "%PROFILE:~0,4%" == "MSVC" (
+ECHO/
+ECHO MSYS2/MinGW
+ECHO -------------------------------------------------------------------------------
+ECHO BUILDDIR_MSYS         = %BUILDDIR_MSYS%
+ECHO INSTDIR_MSYS          = %INSTDIR_MSYS%
+ECHO MSYS2_PATH_TYPE       = %MSYS2_PATH_TYPE%
+ECHO SRCDIR_MSYS           = %SRCDIR_MSYS%
+ECHO PATH                  =
+C:\msys64\usr\bin\bash -lc "echo $PATH"
+)
+ECHO/
+ECHO Windows PATH
+ECHO -------------------------------------------------------------------------------
+ECHO %PATH%
+ECHO ===============================================================================
+ECHO/