try to fix problem...

appveyor.yml

@@ -5,8 +5,6 @@ platform: x64
 cache: c:\tools\vcpkg\installed\
 
 install:
-    # https://stackoverflow.com/questions/44478492/cmake-failed-to-run-msbuild-command-msbuild-exe
-    - set PATH=%PATH%;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin
     - cd C:\projects\libswf && git submodule update --init --recursive
     - call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"
     - cd C:\Tools\vcpkg && git pull && .\bootstrap-vcpkg.bat && cd %APPVEYOR_BUILD_FOLDER%
@@ -15,6 +13,8 @@ install:
 
 before_build:
     - mkdir build && cd build
+    # https://stackoverflow.com/questions/44478492/cmake-failed-to-run-msbuild-command-msbuild-exe
+    - set PATH=%PATH%;C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\MSBuild\Current\Bin
     - cmake ..
        -DCMAKE_BUILD_TYPE:STRING=Release
        -DCMAKE_TOOLCHAIN_FILE=C:/Tools/vcpkg/scripts/buildsystems/vcpkg.cmake