make gem use sudo for macOS (#6610)

gem install requires sudo on official macOS build VMs.
- make bootstrap use sudo for macOS

build.psm1

@@ -1671,9 +1671,14 @@ function Start-PSBootstrap {
             # Install [fpm](https://github.com/jordansissel/fpm) and [ronn](https://github.com/rtomayko/ronn)
             if ($Package) {
                 try {
-                    # We cannot guess if the user wants to run gem install as root
-                    Start-NativeExecution { gem install fpm -v 1.9.3 }
-                    Start-NativeExecution { gem install ronn -v 0.7.3 }
+                    # We cannot guess if the user wants to run gem install as root on linux and windows,
+                    # but macOs usually requires sudo
+                    $gemsudo = ''
+                    if($Environment.IsMacOS) {
+                        $gemsudo = $sudo
+                    }
+                    Start-NativeExecution ([ScriptBlock]::Create("$gemsudo gem install fpm -v 1.9.3"))
+                    Start-NativeExecution ([ScriptBlock]::Create("$gemsudo gem install ronn -v 0.7.3"))
                 } catch {
                     Write-Warning "Installation of fpm and ronn gems failed! Must resolve manually."
                 }

tools/releaseBuild/macOS/PowerShellPackageVsts.ps1

@@ -61,13 +61,6 @@ try {
 
     if ($BootStrap.IsPresent) {
         Start-PSBootstrap -Package
-
-        # The gem install is run by bootstrap without sudo and fails on macOS.
-        # Run the commands with sudo, to resolve the issue
-        Write-Verbose -Message "Installing fpm..." -Verbose
-        Start-NativeExecution { sudo gem install fpm -v 1.8.1 }
-        Write-Verbose -Message "Installing ronn..." -Verbose
-        Start-NativeExecution { sudo gem install ronn }
     }
 
     if ($Build.IsPresent) {