Fix arch detection for i686

This adds detection for the i686 arch and replaces it with x86, allowing
it to build.

BRANCH=none
BUG=none
TEST=Build host_stuff on an i686 machine

Change-Id: Idab7c762a7fbb97ec5318b9aa860756b4dd0bc25
Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-on: https://chromium-review.googlesource.com/645086
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>
diff --git a/Makefile b/Makefile
index 31f714b..2fb0fe4 100644
--- a/Makefile
+++ b/Makefile
@@ -105,6 +105,8 @@
   override ARCH := arm
 else ifeq (${ARCH},i386)
   override ARCH := x86
+else ifeq (${ARCH},i686)
+  override ARCH := x86
 else ifeq (${ARCH},amd64)
   override ARCH := x86_64
 endif