Android: Upgrade ProGuard 5.2.0 -> 6.0.1

Shrinks ChromePublic.apk's classes.dex uncompressed by 110kb

Release notes:
https://www.guardsquare.com/en/blog/proguard-60-released

Change-Id: I237dfb7fb35c33671766c217f838ff559d0a4baf
Reviewed-on: https://chromium-review.googlesource.com/982011
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#546711}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: a1f4e6cb67023ae86fcfe2fc1f8ea5c579994205
diff --git a/README.chromium b/README.chromium
index 14b6982..1e2ec21 100644
--- a/README.chromium
+++ b/README.chromium
@@ -1,7 +1,7 @@
 Name: Proguard
 URL: http://proguard.sourceforge.net/
-Version: 5.2.1
-Date: June 22, 2016
+Version: 6.0.1
+Date: March 4, 2018
 License: GPL v2
 License File: NOT_SHIPPED
 Security Critical: no
diff --git a/lib/proguard.jar b/lib/proguard.jar
index c670fe9..cf011d9 100644
--- a/lib/proguard.jar
+++ b/lib/proguard.jar
Binary files differ
diff --git a/lib/retrace.jar b/lib/retrace.jar
index 408712f..780fd15 100644
--- a/lib/retrace.jar
+++ b/lib/retrace.jar
Binary files differ