CONTRIBUTORS: add Eric Fang, ARM Corporate CLA

Change-Id: I6c6f297d150d25c986b6f57c3661aa5199bc320d
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/221542
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index d56d6f6..bbbb293 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -40,6 +40,7 @@
 David Daney <david.daney@cavium.com>
 Diego Novillo <dnovillo@google.com>
 Dominik Vogt <vogt@linux.vnet.ibm.com>
+Eric Fang <eric.fang@arm.com>
 Ettl Martin <ettl.martin78@googlemail.com>
 Evan Shaw <edsrzf@gmail.com>
 Ian Lance Taylor <iant@golang.org>