CI: Use debug symbols for check to avoid missing .pdb warnings

tools/appveyor/install.ps1

@@ -48,7 +48,7 @@ try {
 
     if ($env:CC_SHORTNAME -eq "vs2015") {
         Write-Host -ForegroundColor Green "`n### Installing libcheck ###`n"
-        & appveyor DownloadFile https://github.com/Pro/check/releases/download/0.12.0_win/check.zip
+        & appveyor DownloadFile https://github.com/Pro/check/releases/download/0.12.0_dbg/check.zip
         & 7z x check.zip -oc:\ -bso0 -bsp0
 
         Write-Host -ForegroundColor Green "`n### Installing DrMemory ###`n"