Fix make and makefile

[matsduf]

CLI has the same problem as Engine with share/Makefile not being compatible with GNU Make on CentOS 7 (zonemaster/zonemaster-engine#813). The solution, as implemented by zonemaster/zonemaster-engine#814, made share/Makefile incompatible with BSD Make (on FreeBSD).

A partial solution to the problem for FreeBSD is proposed in zonemaster/zonemaster-engine#815.

This PR proposes a complete solution to the problem. GNU Make and BSD Make cannot sucessfully use the same Makefile, but GNU Make can be made available on FreeBSD as gmake. And for GNU Make the file GNUmakefile is the preferred file, if available. We use that fact.

• Update Makefile to be GNU Make compatible for CentOS 7 (and incompatible for BSD Make).
• Rename Makefile to GNUmakefile.
• Create wrapper Makefile for BSD Make to make it run the same target as gmake (and GNUmakefile).
• Update Makefile.PL to require gmake for FreeBSD and to use gmake for share/GNUmakefile under FreeBSD.
• Update installation instructions to include the installation of gmake.

The separation into two makefiles will make it possible to update those for future use.

[matsduf]

@sandoche2k, before you test build CLI on CentOS 7, review and test this PR.

[mattias-p]

This is a quite non-trivial change. I don't think we should be merging this kind of thing this close to the release. It's better to adopt the same solution we used in Engine. We can do loftier things for the next release.

[mattias-p]

Why not make both cases use the same variable for the make command?

[matsduf]

The $(MAKE) variable comes from the Makefile. The variable is interpolated by make.

[mattias-p]

I think I would have gone for setting GMAKE to different values on different platforms. That way the "pure_all" clause could be the same for all platforms.

[matsduf]

Such as "GMAKE = $(MAKE)" and "GMAKE = gmake", respectively?

Well, it has the same effect. Please the updated code.

[mattias-p]

Yeah, that's what I had in mind. I'm thinking that it's a little easier on the reader (i.e. us) if you don't have to compare two heavily quoted and generated makefile snippets by eye.

[matsduf]

@mattias-p and @sandoche2k, please review again.

[mattias-p]

@matsduf I can't point to any technical errors in this PR, but do you really think we should make changes of this complexity this close to the release? We have much greater chances of finding problems with the Makefile-GNUmakefile approach if we merge it in the beginning of a release cycle. I think we should go for a more modest solution for this release.

[matsduf]

We have much greater chances of finding problems with the Makefile-GNUmakefile approach if we merge it in the beginning of a release cycle.

It is well-documented that GNU Make prefers GNUmakefile before Makefile. The only problem would be the wrapper function, but that only affects FreeBSD which does not work well with the current situation anyway. I do not see that the risks are higher to implement than to keep it.

I am surprised that we have not seen the solution before instead of trying to make Makefile work for both GNU Make and BSD Make.

[mattias-p]

It's true that GNU make will pick the GNUmakefile.

But it's no beauty queen. I guess that could be a reason why we haven't seen it before. For the next release I'll see if I can't come up with something more satisfying.

[matsduf]

Unless the makefile is very simple it does not seem to be possible to share it between BSD Make and GNU Make. I think this solution of having a wrapper for BSD Make is quite sound. Else we could leave make and use a shell script instead.