chromium: Fix build race condition

[MaxIhlenfeldt]

Fixes #811.

Build and patch changes:

Add one backported patch to fix a build race condition that would sometimes lead to build errors.

License changes:

Added licenses: none.

Removed licenses: none.

Updated licenses: none.

Test-built:

• chromium-wayland:

• nanbield, clang, MACHINE=qemuarm64

• chromium-x11:

• master, clang, MACHINE=qemuarm

[MaxIhlenfeldt]

Builds are still running, I'll merge this once it's approved and the builds have finished successfully.