Upgrade R to 3.4.2

[charpent]

The reasons are the same as usual (getting help on r-help almost requires an up-to-date interpreter.

The original tarball at ​https://cran.r-project.org/src/base/R-3/R-3.4.2.tar.gz .

[charpent]

First attempt :

• installed the upstream tarball un $SAGE_ROOT/upstream ;
• updated version numbers and checksums :
• rebased patches along ​the lines of the Developer's guide.

The resulting R :

• passes ptestlong with no error whatsoever ;
• sort-of passes its own test suite (i. e. a couple of expected, pre-announced, failures)

Patch rebasing : I followed the ​suggestions of the Developer's guide, but for each original patch individually, and manually merged the original patch's initial comment in the new patch.

I still have doubts about the legitimacy of libcurl_https_support.patch, which lift's R enforcement of https support. I am aware that Jeroen was sanguine about not enforcing the use of openssl, but do not know if he maintains this position in view of the recent (ongoing ?) ​change of license. Furthermore, I think that switching as much as possible to authenticated Web sources is a Good Idea (TM), and that this move is almost irresistible ; I still don't like to fight the weather...

A usual, I think that this should be checked on out problem children of platforms :

• Macintosh,
• Windows on Cygwin (at least 64 bits).

Hence the Cc to Dimitri (who is, AFAICT, the most knowledgeable Sage developer about Macs and their shenanigans) and Erik (whose heroic port to Cygwin is a major boon to Sage).

needs_review

---

New commits:

​f6a8c89

24026 : rebased patches, updated version.

[dimpase]

works on OSX (10.12), and on FreeBSD. (Disclaimer --- I don't use OSX for work since many years already, I just still have an old and slow MacBook Air on which I can test things).

As OSX support on 10.12 is currently dependent on open tickets, this is a test done with clang as the main C compiler, using #12426, and gfortran built using #23898.

[embray]

LGTM on Cygwin