Build the runtime of all the Windows architectures before building SDKs

In order to get the 'built swift compiler' to work before building the
SDK components so that regardless of the order of architectures in the
`WindowsSDKs`. This previously worked because X64 happened to be the
first in `WindowsSDKs` and we always built on X64. This avoids a build
failure in the Windows ARM64 libdispatch build on Windows ARM64 caused
by the Windows ARM64 runtime that hasn't been built yet.

Author: hjyamauchi

utils/build.ps1

@@ -2799,9 +2799,10 @@ if (-not $SkipBuild) {
     Invoke-BuildStep Build-XML2 Windows $Arch
     Invoke-BuildStep Build-CURL Windows $Arch
     Invoke-BuildStep Build-LLVM Windows $Arch
-
-    # Build platform: SDK, Redist and XCTest
     Invoke-BuildStep Build-Runtime Windows $Arch
+  }
+  foreach ($Arch in $WindowsSDKArchs) {
+    # Build platform: SDK, Redist and XCTest
     Invoke-BuildStep Build-Dispatch Windows $Arch
     # FIXME(compnerd) ensure that the _build_ is the first arch and don't rebuild on each arch
     Invoke-BuildStep Build-FoundationMacros -Build Windows $BuildArch