Add DESTDIR support for r, and other cleanup

[embray]

Implements #24024, incorporating changes to the spkg-install for R originally from #22509 as well as #23733.

CC: @dimpase

Component: build

Author: Erik Bray

Branch/Commit: dc342ae

Reviewer: Julian Rüth, Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/25049

[embray]

comment:1

This already got some pretty good OSX testing when it was part of #22509, but that was a while ago so it should be tested again.

[embray]

comment:2

Tested on OSX 10.13 and it works--R builds, its installed files are correctly listed in the manifest, and it runs at least basically.

[saraedum]

comment:4

Looks good. Is the build script now run with a set -e so no error checking needs to be done explicitly anymore?

[saraedum]

Reviewer: Julian Rüth

[embray]

comment:5

I'm not sure I understand your question about error checking, but it might be related to #23179. Ever since that ticket all the stuff about checking that $SAGE_LOCAL is set is not necessary when writing spkg installers.

[saraedum]

comment:6

Hm…I had a look at #23179 but I could not find the bit I was looking for so let me rephrase my question. I can not find a set -e at the top of the proposed spkg-install script. Is that not necessary anymore? Is this somehow set from the outside now?

[jdemeyer]

comment:8

Can't we get rid of the "move old installs" part? Doesn't DESTDIR solve that problem?

[jdemeyer]

comment:9

Replying to @saraedum:

Looks good. Is the build script now run with a set -e

No: set -e was not used before and it is still not used.