chore: remove mips64el patches as they've largely been upstreamed (#18628)

patches/chromium/thread_capabilities.patch

@@ -0,0 +1,27 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Anonymous <anonymous@electronjs.org>
+Date: Thu, 20 Sep 2018 17:46:43 -0700
+Subject: thread_capabilities.patch
+
+Chromium automatically drops all capabilities of renderer threads in
+Linux, which may cause issues in a context like Electron, where the main
+and renderer threads are supposed to keep inherited permissions over the
+system.
+
+See https://github.com/atom/electron/issues/3666
+
+diff --git a/sandbox/linux/services/credentials.cc b/sandbox/linux/services/credentials.cc
+index 542567f3ee58776a8ca915f1f62dcffa29141798..0f5f017b0ee63bbe7107f39143484bc6d728104e 100644
+--- a/sandbox/linux/services/credentials.cc
++++ b/sandbox/linux/services/credentials.cc
+@@ -352,8 +352,10 @@ pid_t Credentials::ForkAndDropCapabilitiesInChild() {
+     return pid;
+   }
+ 
++#if 0
+   // Since we just forked, we are single threaded.
+   PCHECK(DropAllCapabilitiesOnCurrentThread());
++#endif
+   return 0;
+ }
+