Annotate large droidstubs modules high_mem

Previously all droidstubs modules were classified as highmem. Annotate
only the huge modules as such, to allow more parallelization of lowmem
droidstubs modules.

Bug: 170701554
Test: NINJA_HIGHMEM_NUM_JOBS=3 m checkapi
Change-Id: I83ae88222110d7afe4009076e951c88a5188ca83
diff --git a/StubLibraries.bp b/StubLibraries.bp
index 39aa732..e0c3022 100644
--- a/StubLibraries.bp
+++ b/StubLibraries.bp
@@ -73,6 +73,7 @@
         "android.hardware.vibrator-V1.3-java",
         "framework-protos",
     ],
+    high_mem: true, // Lots of sources => high memory use, see b/170701554
     installable: false,
     annotations_enabled: true,
     previous_api: ":android.api.public.latest",