build: only check REPLACEME & DEP...X for releases

[rvagg]

A rehash of #12958.

Summary: the introduction of the checks for REPLACEME and later DEP...X in the release-only Makefile target screwed up "test" and "rc" builds. There are exclusions for "nightly" and "next-nightly" because those are automatic and IIRC we noticed those builds stopped working shortly after the REPLACEME check was instituted. However, "test" and "rc" builds are manual and don't work with this check. Now we also have "v8-canary" in the mix too. These extras make use of the "custom" DISTTYPE.

This got held up because there was disagreement about how exclusive to be. The original change proposed in #8325 was similar to this one but it was then made exclusive by switching to the "nightly" and "next-nightly" builds.

For the last ~18 months we've had this in ci-release:

if [[ "X${disttype}" != "Xrelease" ]]; then
  perl -pi -e "s/: release-only/:/g" Makefile
fi

i.e. overriding the release-only target in Makefile for everything but "release" builds.

This PR aims to put that logic into Makefile so we can remove that check.

Ref: #24551
Ref: #12958
Ref: #12957
Ref: #8325

[nodejs-github-bot]

@rvagg build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/1682/pipeline

[rvagg]

Landed in 89e8fc4

[rvagg]

I've removed this from all over iojs+release:

if [[ "X${disttype}" != "Xrelease" ]]; then
  perl -pi -e "s/: release-only/:/g" Makefile
fi

So @nodejs/build & @nodejs/releasers need to keep an eye out for funny behaviour, it's been in place for a long time.

I've kicked off a test build and a rerun of the last nightly build, just to test. Tomorrow I might try a re-do of one of today's releases and then clean it up from staging.