Use a bool for ForceDefaults instead of an int

The actual function takes a bool.

While we are doing this, add a couple missing ForceDefaults.

Change-Id: I7fd41c048dae340ca4f339230ceb033349db0faf
diff --git a/aos/flatbuffer_merge_test.cc b/aos/flatbuffer_merge_test.cc
index 371639a..890a831 100644
--- a/aos/flatbuffer_merge_test.cc
+++ b/aos/flatbuffer_merge_test.cc
@@ -136,7 +136,7 @@
         out);
     {
       flatbuffers::FlatBufferBuilder fbb;
-      fbb.ForceDefaults(1);
+      fbb.ForceDefaults(true);
       fbb.Finish(MergeFlatBuffers(
           ConfigurationTypeTable(),
           flatbuffers::GetRoot<flatbuffers::Table>(fb1.data()),
@@ -145,7 +145,7 @@
     }
     {
       flatbuffers::FlatBufferBuilder fbb;
-      fbb.ForceDefaults(1);
+      fbb.ForceDefaults(true);
       fbb.Finish(MergeFlatBuffers<Configuration>(
           flatbuffers::GetRoot<flatbuffers::Table>(fb1.data()),
           flatbuffers::GetRoot<flatbuffers::Table>(fb2.data()), &fbb));