build: add a -Clean option to build.ps1

When the compiler changes, the SDK and tool builds do not notice the
compiler change due to the missing compiler tracking. This allows us to
quickly perform an incremental by not discarding the compiler build.

Author: compnerd

utils/build.ps1

@@ -101,6 +101,7 @@ param(
   [string[]] $Test = @(),
   [string] $Stage = "",
   [string] $BuildTo = "",
+  [switch] $Clean,
   [switch] $DebugInfo,
   [switch] $EnableCaching,
   [switch] $ToBatch
@@ -1743,6 +1744,13 @@ if (-not $SkipBuild) {
   Invoke-BuildStep Build-Compilers $HostArch
 }
 
+if ($Clean) {
+  2..16 | % { Remove-Item -Force -Recurse "$BinaryCache\$_" -ErrorAction Ignore }
+  foreach ($Arch in $SDKArchs) {
+    0..3 | % { Remove-Item -Force -Recurse "$BinaryCache\$($Arch.BuildiD + $_)" -ErrorAction Ignore }
+  }
+}
+
 foreach ($Arch in $SDKArchs) {
   if (-not $SkipBuild) {
     Invoke-BuildStep Build-ZLib $Arch