Move trapezoid_profile.cc to Python

Change-Id: Ifac28aaabb24a668b04371edbeb58717c49c8925
diff --git a/aos/common/util/BUILD b/aos/common/util/BUILD
index cbaf8ba..4437ef6 100644
--- a/aos/common/util/BUILD
+++ b/aos/common/util/BUILD
@@ -1,5 +1,12 @@
 package(default_visibility = ['//visibility:public'])
 
+py_library(
+  name = 'py_trapezoid_profile',
+  srcs = [
+    'trapezoid_profile.py',
+  ],
+)
+
 cc_library(
   name = 'run_command',
   srcs = [