[windows] add usr/lib/swift/clang to the toolchain installer

this directory contains clang's resource headers that are needed by the clang embedded inside of the swift compiler, as it assumes its clang resources are in usr/lib/swift/clang, as opposed to standalone clang looking in usr/lib/clang/<clang_version>

Author: hyp

platforms/Windows/bld/bld.wixproj

@@ -5,6 +5,7 @@
       DEVTOOLS_ROOT=$(DEVTOOLS_ROOT);
       TOOLCHAIN_ROOT=$(TOOLCHAIN_ROOT);
       TOOLCHAIN_ROOT_USR_LIB_CLANG=$(TOOLCHAIN_ROOT)\usr\lib\clang;
+      TOOLCHAIN_ROOT_USR_LIB_SWIFT_CLANG=$(TOOLCHAIN_ROOT)\usr\lib\swift\clang;
     </DefineConstants>
   </PropertyGroup>
 
@@ -22,4 +23,15 @@
       <SuppressRootDirectory>true</SuppressRootDirectory>
     </HarvestDirectory>
   </ItemGroup>
+
+  <ItemGroup>
+    <HarvestDirectory Include="$(TOOLCHAIN_ROOT)\usr\lib\swift\clang">
+      <ComponentGroupName>SwiftClangResources</ComponentGroupName>
+      <DirectoryRefId>_usr_lib_swift_clang</DirectoryRefId>
+      <PreprocessorVariable>var.TOOLCHAIN_ROOT_USR_LIB_SWIFT_CLANG</PreprocessorVariable>
+      <SuppressCom>true</SuppressCom>
+      <SuppressRegistry>true</SuppressRegistry>
+      <SuppressRootDirectory>true</SuppressRootDirectory>
+    </HarvestDirectory>
+  </ItemGroup>
 </Project>

platforms/Windows/bld/bld.wxs

@@ -506,6 +506,7 @@
       <ComponentGroupRef Id="TestingMacros" />
 
       <ComponentGroupRef Id="ClangResources" />
+      <ComponentGroupRef Id="SwiftClangResources" />
 
       <ComponentGroupRef Id="EnvironmentVariables" />
       <ComponentGroupRef Id="VersionedDirectoryCleanup" />

platforms/Windows/shared/shared.wxs

@@ -44,7 +44,9 @@
               <Directory Id="_usr_include" Name="include" />
               <Directory Id="_usr_lib" Name="lib">
                 <Directory Id="_usr_lib_clang" Name="clang" />
-                <Directory Id="_usr_lib_swift" Name="swift" />
+                <Directory Id="_usr_lib_swift" Name="swift">
+                  <Directory Id="_usr_lib_swift_clang" Name="clang" />
+                </Directory>
               </Directory>
               <Directory Id="_usr_share" Name="share">
                 <Directory Id="_usr_share_docc" Name="docc">