Rasmus noted that the failure path didn't correctly exit. Fix this and
add another comment about GNU Make's job server environment variable
names over time.
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/lkml/eb25959a-9ec4-3530-2031-d9d716b40b20@rasmusvillemoes.dkSigned-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20191121205929.40371-2-keescook@chromium.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>