[PATCH] build: fix out-of-tree builds

[David Bremner]

Jani Nikula <jani at nikula.org> writes:
>  # List all subdirectories here. Each contains its own Makefile.local
> -subdirs := compat completion emacs lib man parse-time-string
> -subdirs += performance-test util test
> +subdirs = compat completion emacs lib man parse-time-string performance-test util test

Is this a functional change or a cosmetic one?

d