Build log_index using scons

SConstruct

@@ -249,5 +249,7 @@ if arch == "aarch64":
 
 SConscript(['selfdrive/locationd/SConscript'])
 SConscript(['selfdrive/locationd/kalman/SConscript'])
+SConscript(['tools/lib/index_log/SConscript'])
+
 
 # TODO: finish cereal, dbcbuilder, MPC

tools/lib/index_log/SConscript

@@ -0,0 +1,3 @@
+Import('env', 'arch', 'messaging')
+
+env.Program('index_log', ['index_log.cc'], LIBS=[messaging, 'kj', 'capnp'])

tools/lib/logreader.py

@@ -23,9 +23,10 @@ OP_PATH = os.path.dirname(os.path.dirname(capnp_log.__file__))
 def index_log(fn):
   index_log_dir = os.path.join(os.path.dirname(os.path.realpath(__file__)), "index_log")
   index_log = os.path.join(index_log_dir, "index_log")
-  phonelibs_dir = os.path.join(OP_PATH, 'phonelibs')
 
-  subprocess.check_call(["make", "PHONELIBS=" + phonelibs_dir], cwd=index_log_dir, stdout=subprocess.DEVNULL)
+  if not os.path.exists(index_log):
+    phonelibs_dir = os.path.join(OP_PATH, 'phonelibs')
+    subprocess.check_call(["make", "PHONELIBS=" + phonelibs_dir], cwd=index_log_dir, stdout=subprocess.DEVNULL)
 
   try:
     dat = subprocess.check_output([index_log, fn, "-"])