display: Build composer in headless mode

Change-Id: I4d10b71fd6ddf35361899bde91b554cda196bbb8
diff --git a/composer/hwc_tonemapper.cpp b/composer/hwc_tonemapper.cpp
index d417258..a88c06f 100644
--- a/composer/hwc_tonemapper.cpp
+++ b/composer/hwc_tonemapper.cpp
@@ -63,6 +63,7 @@
 void ToneMapSession::OnTask(const ToneMapTaskCode &task_code,
                             SyncTask<ToneMapTaskCode>::TaskContext *task_context) {
   switch (task_code) {
+#ifndef TARGET_HEADLESS
     case ToneMapTaskCode::kCodeGetInstance: {
         ToneMapGetInstanceContext *ctx = static_cast<ToneMapGetInstanceContext *>(task_context);
         Lut3d &lut_3d = ctx->layer->lut_3d;
@@ -95,6 +96,7 @@
       }
       break;
 
+#endif
     default:
       break;
   }