[boost generate-ports] Derive port-version from master baseline

scripts/boost/generate-ports.ps1

@@ -25,22 +25,21 @@ if ($null -eq $vcpkg) {
 # Beta builds contains a text in the version string
 $semverVersion = ($version -replace "(\d+(\.\d+){1,3}).*", "`$1")
 
-# Clear this array when moving to a new boost version
-$defaultPortVersion = 1
-$portVersions = @{
-}
+"Downloading baseline.json from master..."
+Invoke-WebRequest -Uri "https://github.com/microsoft/vcpkg/raw/master/versions/baseline.json" -OutFile "$scriptsDir/baseline.json"
+
+$baseline = Get-Content -LiteralPath "$scriptsDir/baseline.json" -Raw `
+| ConvertFrom-Json `
+| Select-Object -ExpandProperty 'default'
 
 function Get-PortVersion {
     param (
         [string]$PortName
     )
-
-    $nonDefault = $portVersions[$PortName]
-    if ($null -ne $nonDefault) {
-        return $nonDefault
+    if ($baseline.$PortName.baseline -eq $semverVersion) {
+        return $baseline.$PortName.'port-version' + 1
     }
-
-    return $defaultPortVersion
+    return 0
 }
 
 $portData = @{