Merge pull request #2414 from shenki/buildroot-2018.08.1

buildroot: Move to 2018.08.1 point release
diff --git a/buildroot b/buildroot
index 28df4d3..42b8cdf 160000
--- a/buildroot
+++ b/buildroot
@@ -1 +1 @@
-Subproject commit 28df4d3f32cdb7dd573f64062c21b8bcfeffebba
+Subproject commit 42b8cdf841eb7ef413c791fc24ad111400fc9cd1