appveyor: upgrade to msvc 2019.

appveyor.yml

@@ -1,17 +1,14 @@
 version: build{build}
-image: Visual Studio 2015
+image: Visual Studio 2019
 
 environment:
   WIRESHARK_BASE_DIR: C:\wireshark-libs
   matrix:
     # Note: if VS2017 win32 is added, just use Qt msvc2015 (binary compatible).
     - PLATFORM: x64
-      CMAKE_GENERATOR: Visual Studio 15 2017 Win64
-      QT5_BASE_DIR: C:\Qt\5.11\msvc2017_64
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-    - PLATFORM: x64
-      CMAKE_GENERATOR: Visual Studio 14 2015 Win64
-      QT5_BASE_DIR: C:\Qt\5.11\msvc2015_64
+      CMAKE_GENERATOR: Visual Studio 16 2019
+      QT5_BASE_DIR: C:\Qt\5.15\msvc2019_64
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
 
 cache:
   - '%WIRESHARK_BASE_DIR%'
@@ -23,11 +20,15 @@ install:
   # Java is already installed, prevent an expensive upgrade (102 seconds).
   - choco install --ignore-dependencies asciidoctorj docbook-bundle xsltproc
   # Py2 fails the test_tshark_unicode_display_filter test, so use Py3.
-  - set PATH=C:\Python37-x64;C:\Python37-x64\Scripts;%PATH%
+  - set PATH=C:\Strawberry\perl\bin\;C:\Python37-x64;C:\Python37-x64\Scripts;%PATH%
   - pip install pytest pytest-xdist
+  - ps: New-Item -ItemType Directory -Force -Path $Env:WIRESHARK_BASE_DIR
   - ps: |   # For pkcs11 tests.
       Invoke-WebRequest -Uri https://github.com/disig/SoftHSM2-for-Windows/releases/download/v2.5.0/SoftHSM2-2.5.0.msi -OutFile $Env:WIRESHARK_BASE_DIR\SoftHSM2-2.5.0.msi
       & msiexec /qn /i $Env:WIRESHARK_BASE_DIR\SoftHSM2-2.5.0.msi
+  # https://help.appveyor.com/discussions/questions/18777-how-to-use-vcvars64bat-from-powershell
+  - ps: cmd.exe /c "call `"C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat`" && set > %temp%\vcvars.txt"
+  - ps: Get-Content "$env:temp\vcvars.txt" | Foreach-Object { if ($_ -match "^(.*?)=(.*)$") { Set-Content "env:\$($matches[1])" $matches[2] } }
 
 # Note: the NSIS installer lacks debug dlls for Debug builds.
 configuration: RelWithDebInfo
@@ -40,7 +41,7 @@ before_build:
   - perl tools/make-version.pl --set-release --untagged-version-extra=-{vcsinfo}-AppVeyor --tagged-version-extra=-AppVeyor
   - mkdir build
   - cd build
-  - cmake -E time cmake -G "%CMAKE_GENERATOR%" ..
+  - cmake -E time cmake -DCMAKE_SYSTEM_VERSION=10.0.20348.0 -G "%CMAKE_GENERATOR%" ..
 
 after_build:
   - msbuild /m nsis_package_prep.vcxproj