Set VCPKG_ROOT (#3938)

* Set VCPKG_ROOT

* Update eng/pipelines/templates/steps/vcpkg-clone.yml

Co-authored-by: Ben Broderick Phillips <bebroder@microsoft.com>

Co-authored-by: Ben Broderick Phillips <bebroder@microsoft.com>

eng/pipelines/templates/stages/archetype-cpp-release.yml

@@ -144,6 +144,7 @@ stages:
                         parameters:
                           RepoOwner: Azure
                           RepoName: azure-sdk-vcpkg-betas
+                          SetVcpkgRoot: false
 
                       - template: /eng/pipelines/templates/steps/vcpkg-publish.yml
                         parameters:

eng/pipelines/templates/steps/vcpkg-clone.yml

@@ -3,6 +3,7 @@ parameters:
   RepoOwner: not-set
   RepoName: vcpkg
   PRBranchName: not-set
+  SetVcpkgRoot: true
 
 steps:
   - pwsh: |
@@ -14,6 +15,13 @@ steps:
       }
     displayName: Clone vcpkg (${{ parameters.RepoOwner }}/${{ parameters.RepoName }})
 
+  - ${{ if eq(parameters.SetVcpkgRoot, true) }}:
+    - pwsh: |
+        $vcpkgRoot = Resolve-Path "${{ parameters.Workspace }}/${{ parameters.RepoName }}"
+        Write-Host "Set VCPKG_ROOT: $vcpkgRoot"
+        Write-Host "##vso[task.setvariable variable=VCPKG_ROOT]$vcpkgRoot"
+      displayName: Set VCPKG_ROOT
+
   # Check out the PR branch if it's already in remote. Ignore failures.
   - pwsh: |
       $ErrorActionPreference = "Continue"