Define SwiftBuild_Dir when building SwiftPM in build.ps1

Author: owenv

utils/build.ps1

@@ -2821,6 +2821,7 @@ function Build-PackageManager([Hashtable] $Platform) {
       LLBuild_DIR = (Get-ProjectCMakeModules $Platform LLBuild);
       ArgumentParser_DIR = (Get-ProjectCMakeModules $Platform ArgumentParser);
       SwiftDriver_DIR = (Get-ProjectCMakeModules $Platform Driver);
+      SwiftBuild_DIR = (Get-ProjectCMakeModules $Platform Build);
       SwiftCrypto_DIR = (Get-ProjectCMakeModules $Platform Crypto);
       SwiftCollections_DIR = (Get-ProjectCMakeModules $Platform Collections);
       SwiftASN1_DIR = (Get-ProjectCMakeModules $Platform ASN1);
@@ -2945,6 +2946,7 @@ function Build-SourceKitLSP([Hashtable] $Platform) {
       ArgumentParser_DIR = (Get-ProjectCMakeModules $Platform ArgumentParser);
       SwiftCrypto_DIR = (Get-ProjectCMakeModules $Platform Crypto);
       SwiftCollections_DIR = (Get-ProjectCMakeModules $Platform Collections);
+      SwiftBuild_DIR = (Get-ProjectCMakeModules $Platform Build);
       SwiftPM_DIR = (Get-ProjectCMakeModules $Platform PackageManager);
       LMDB_DIR = (Get-ProjectCMakeModules $Platform LMDB);
       IndexStoreDB_DIR = (Get-ProjectCMakeModules $Platform IndexStoreDB);