[ci] Enable CodeQL static analysis. (#1409)

Author: jpobst

.ci/build.yml

@@ -63,18 +63,23 @@ jobs:
           linux:
             poolName: ${{ parameters.linuxAgentPoolName }}
             imageName: ${{ parameters.linuxImage }}
+            runCodeQL: false
         ${{ if ne(parameters.macosImage, '') }}:
           macos:
             poolName: ${{ parameters.macosAgentPoolName }}
             imageName: ${{ parameters.macosImage }}
+            runCodeQL: false
         ${{ if ne(parameters.windowsImage, '') }}:
           windows:
             poolName: ${{ parameters.windowsAgentPoolName }}
             imageName: ${{ parameters.windowsImage }}
+            runCodeQL: true
     displayName: ${{ parameters.displayName }}
     timeoutInMinutes: ${{ parameters.timeoutInMinutes }}
     continueOnError: ${{ eq(parameters.continueOnError, 'true') }}
     dependsOn: ${{ parameters.dependsOn }}
+    variables:
+      Codeql.Enabled: $(runCodeQL)
     pool:
       name: $(poolName)
       vmImage: $(imageName)