Modified install to only install what's required for BUILD

Author: clanmills

appveyor_mingw_cygwin.yml

@@ -24,17 +24,17 @@ shallow_clone: true
 
 install:
     - echo %APPVEYOR_BUILD_FOLDER%
-    - set "PATH=c:\msys64\mingw64\bin;c:\msys64\usr\bin;c:\msys64\usr\local\bin;"
-    - C:\msys64\usr\bin\bash -c "python -m pip install --upgrade pip;pip3.exe install lxml ; for i in base-devel git coreutils dos2unix tar diffutils make  \
+    - if "%BUILD%"=="MINGW64" set "PATH=c:\msys64\mingw64\bin;c:\msys64\usr\bin;c:\msys64\usr\local\bin;"
+    - if "%BUILD%"=="MINGW64" C:\msys64\usr\bin\bash -c "python -m pip install --upgrade pip;pip3.exe install lxml ; for i in base-devel git coreutils dos2unix tar diffutils make  \
          mingw-w64-x86_64-toolchain mingw-w64-x86_64-gcc      mingw-w64-x86_64-gdb     \
          mingw-w64-x86_64-cmake     mingw-w64-x86_64-gettext  mingw-w64-x86_64-python3 \
          mingw-w64-x86_64-libexpat  mingw-w64-x86_64-libiconv mingw-w64-x86_64-zlib    \
          mingw-w64-x86_64-gtest ; do (echo y | pacman -S $i) ; done
     - cd %APPVEYOR_BUILD_FOLDER%
-    - set "PATH=c:\cygwin64\usr\local\bin;c:\cygwin64\bin;c:\cygwin64\usr\bin;c:\cygwin64\usr\sbin;"
-    - C:\cygwin64\bin\bash -c "wget https://raw.githubusercontent.com/transcode-open/apt-cyg/master/apt-cyg ; chmod +x apt-cyg; mv apt-cyg /usr/local/bin"
-    - C:\cygwin64\bin\bash -c "apt-cyg install cmake zlib-devel libexpat-devel libxml2-devel libxslt-devel python38 python38-pip python38-libxml2"
-    - C:\cygwin64\bin\bash -c "/usr/bin/python3.8.exe -m pip install --upgrade pip"
+    - if "%BUILD%"=="CYGWIN64" set "PATH=c:\cygwin64\usr\local\bin;c:\cygwin64\bin;c:\cygwin64\usr\bin;c:\cygwin64\usr\sbin;"
+    - if "%BUILD%"=="CYGWIN64" C:\cygwin64\bin\bash -c "wget https://raw.githubusercontent.com/transcode-open/apt-cyg/master/apt-cyg ; chmod +x apt-cyg; mv apt-cyg /usr/local/bin"
+    - if "%BUILD%"=="CYGWIN64" C:\cygwin64\bin\bash -c "apt-cyg install cmake zlib-devel libexpat-devel libxml2-devel libxslt-devel python38 python38-pip python38-libxml2"
+    - if "%BUILD%"=="CYGWIN64" C:\cygwin64\bin\bash -c "/usr/bin/python3.8.exe -m pip install --upgrade pip"
 
 build_script:
     - cmd: set   CMD=mkdir -p build