Add missing clean-up of idmap file descriptors.

Change-Id: I9bdc9a4b7962f1a8dce77f4b213c8b9dc26e4b0f
diff --git a/libs/utils/AssetManager.cpp b/libs/utils/AssetManager.cpp
index 13004cd..0b4d1ac 100644
--- a/libs/utils/AssetManager.cpp
+++ b/libs/utils/AssetManager.cpp
@@ -680,6 +680,9 @@
                 delete ass;
             }
         }
+        if (idmap != NULL) {
+            delete idmap;
+        }
     }
 
     if (required && !rt) LOGW("Unable to find resources file resources.arsc");