Add constants.h which contains the result of calibration.

Change-Id: Ia7f76ff9bd549728c40888e800ebc266769525db
diff --git a/y2019/vision/BUILD b/y2019/vision/BUILD
index c2f9da5..bdef187 100644
--- a/y2019/vision/BUILD
+++ b/y2019/vision/BUILD
@@ -10,6 +10,12 @@
 ]
 
 cc_library(
+    name = "constants",
+    hdrs = ["constants.h"],
+    srcs = ["constants.cc"],
+)
+
+cc_library(
     name = "target_finder",
     srcs = [
         "target_finder.cc",
@@ -21,6 +27,7 @@
     ],
     restricted_to = VISION_TARGETS,
     deps = [
+        ":constants",
         "//aos/vision/blob:contour",
         "//aos/vision/blob:hierarchical_contour_merge",
         "//aos/vision/blob:region_alloc",