add clcache to Windows build

Author: Daniel Kroening

buildspec-windows.yml

@@ -5,6 +5,7 @@ phases:
     commands:
       - choco install cyg-get -y --no-progress
       - cyg-get bash patch bison flex make wget perl
+      - nuget install clcache -OutputDirectory "c:\tools\cygwin\bin"
 
   build:
     commands:
@@ -14,13 +15,13 @@ phases:
 
       - |
         $env:Path = "C:\tools\cygwin\bin;$env:Path"
-        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make -j4 -C src BUILD_ENV=MSVC" '
-        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make -j4 -C unit all BUILD_ENV=MSVC" '
+        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make CXX=clcache -j4 -C src BUILD_ENV=MSVC" '
+        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make CXX=clcache -j4 -C unit all BUILD_ENV=MSVC" '
 
       - |
         $env:Path = "C:\tools\cygwin\bin;$env:Path"
-        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make -j4 -C jbmc/src setup-submodules" && bash -c "make -j4 -C jbmc/src BUILD_ENV=MSVC" '
-        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make -j4 -C jbmc/unit all BUILD_ENV=MSVC" '
+        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make -j4 -C jbmc/src setup-submodules" && bash -c "make CXX=clcache -j4 -C jbmc/src BUILD_ENV=MSVC" '
+        cmd /c 'call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64 && bash -c "make CXX=clcache -j4 -C jbmc/unit all BUILD_ENV=MSVC" '
 
   post_build:
     commands: