Bump corefx to get mono/corefx#395 (#19426)

monojenkins · mdh1418 · web-flow · commit b04dc7e6a48c · 2020-04-03T19:40:04.000+02:00
Co-authored-by: Mitchell Hwang &lt;mihw@microsoft.com&gt;
diff --git a/external/corefx b/external/corefx
@@ -1 +1 @@
-Subproject commit 7c9e2158925339a5a96ff8d09d21c600a0b27e5a
+Subproject commit bec934370587bdbe8a9e4305a5e9167dd7b63677
