fix cmake vcpkg.cmake warning

tools/appveyor/build.ps1

@@ -18,6 +18,9 @@ if ($env:CC_SHORTNAME -eq "mingw") {
 } else {
     $vcpkg_toolchain = '-DCMAKE_TOOLCHAIN_FILE="C:/Tools/vcpkg/scripts/buildsystems/vcpkg.cmake"'
     $vcpkg_triplet = '-DVCPKG_TARGET_TRIPLET="x86-windows-static"'
+    # since https://github.com/Microsoft/vcpkg/commit/0334365f516c5f229ff4fcf038c7d0190979a38a#diff-464a170117fa96bf98b2f8d224bf503c
+    # vcpkg need to have  "C:\Tools\vcpkg\installed\x86-windows-static"
+    New-Item -Force -ItemType directory -Path "C:\Tools\vcpkg\installed\x86-windows-static"
 }
 
 
@@ -152,4 +155,4 @@ if ($env:CC_SHORTNAME -eq "vs2015") {
 }
 
 # do not cache log
-Remove-Item -Path c:\miktex\texmfs\data\miktex\log -Recurse -Force
+Remove-Item -Path c:\miktex\texmfs\data\miktex\log -Recurse -Force