Ensure appropriate minimum alignment on flatbuffer tables

If you had a table whose fields all had alignments of <4 bytes, the
overall table still needed to have 4 byte alignment to account for the
various offsets included in every table.

Change-Id: I7c39c647d79dff80732f84c4e530319ee8f20c99
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/flatbuffers/static_flatbuffers.cc b/aos/flatbuffers/static_flatbuffers.cc
index 502e33e..7b42ef6 100644
--- a/aos/flatbuffers/static_flatbuffers.cc
+++ b/aos/flatbuffers/static_flatbuffers.cc
@@ -627,9 +627,9 @@
     }
   }
 
-  const std::string alignment =
-      absl::StrCat("static constexpr size_t kAlign = std::max<size_t>({",
-                   absl::StrJoin(alignments, ", "), "});\n");
+  const std::string alignment = absl::StrCat(
+      "static constexpr size_t kAlign = std::max<size_t>({kMinAlign, ",
+      absl::StrJoin(alignments, ", "), "});\n");
   const std::string size =
       absl::StrCat("static constexpr size_t kSize = ",
                    AlignCppString(offset_data_start_expression + " + " +