build: don't fail `make test` on source tarballs
Tries to achieve the same effect as https://github.com/nodejs/node/pull/13658 without breaking source tarballs. Presumably if tools/eslint
wasn't there at all, people would notice in the PR review!
Fixes: https://github.com/nodejs/node/issues/14513
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
build