WiX: require DocC for packaging the Windows toolchain

In order to save time, converting DocC to CMake shaves ~8% of the
overall Windows toolchain build time. At this point, it makes sense to
make this is a required component as it can be built with CMake.

platforms/Windows/cli/cli.wixproj

@@ -5,17 +5,13 @@
       DEVTOOLS_ROOT=$(DEVTOOLS_ROOT);
       TOOLCHAIN_ROOT=$(TOOLCHAIN_ROOT);
       SWIFT_DOCC_BUILD=$(SWIFT_DOCC_BUILD);
-      INCLUDE_SWIFT_DOCC=$(INCLUDE_SWIFT_DOCC);
       SWIFT_FORMAT_BUILD=$(SWIFT_FORMAT_BUILD);
       SWIFT_DOCC_RENDER_ARTIFACT_ROOT_DIST=$(SWIFT_DOCC_RENDER_ARTIFACT_ROOT)\dist;
     </DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="WixToolset.Heat" Version="4.0.1" />
-  </ItemGroup>
-
-  <ItemGroup Condition="'$(INCLUDE_SWIFT_DOCC)' == 'true'">
     <HarvestDirectory Include="$(SWIFT_DOCC_RENDER_ARTIFACT_ROOT)\dist">
       <ComponentGroupName>DocCRender</ComponentGroupName>
       <DirectoryRefId>_usr_share_docc_render</DirectoryRefId>

platforms/Windows/cli/cli.wxs

@@ -232,11 +232,9 @@
     </ComponentGroup>
 
     <ComponentGroup Id="DocC" Directory="_usr_bin">
-      <?if $(INCLUDE_SWIFT_DOCC) == true ?>
-        <Component>
-          <File Source="$(SWIFT_DOCC_BUILD)\docc.exe" />
-        </Component>
-      <?endif?>
+      <Component>
+        <File Source="$(TOOLCHAIN_ROOT)\usr\bin\docc.exe" />
+      </Component>
     </ComponentGroup>
 
     <ComponentGroup Id="swift_format" Directory="_usr_bin">
@@ -261,9 +259,7 @@
       <ComponentGroupRef Id="package_manager" />
 
       <ComponentGroupRef Id="DocC" />
-      <?if $(INCLUDE_SWIFT_DOCC) == true ?>
-        <ComponentGroupRef Id="DocCRender" />
-      <?endif?>
+      <ComponentGroupRef Id="DocCRender" />
 
       <ComponentGroupRef Id="swift_format" />