[R-SIG-Mac] R 4.0: many PCRE JIT compilation errors

[Daniel Kelley]

I am  trying to build the "oce" package, and I get many (tens of thousands) of warnings of form similar to

```R
Warning in gsub("\n \\.([^\n])", "\n  .\\1", gsub("\n[ \t]*\n", "\n .\n ",  :
  PCRE JIT compilation error
	'no more memory'
```

I am working through the build/check/install in stages, and documenting things at

https://github.com/dankelley/oce/issues/1674

in case that's of any help to anyone else.  Perhaps my grep() and gsub() calls are poorly framed, but I've never seen this warning before, and I suspect the warnings (or some of them) may be coming from he "R CMD" stage itself, so my guess is that this is an indication of a problem with R-4.0/macos.

I wish to note my deep thanks to the team behind macos development for R.

PS. I'm glad to hear that there may be an upcoming macos equivalent to winbuilder, because I have had very uneven success with rhub (working one day, failing another, on identical code, etc).

Dan E. Kelley [he/him/his 314ppm]
Professor and Senator
Department of Oceanography
Dalhousie University
PO BOX 15000
Halifax, NS, Canada B3H 4R2
Dan.Kelley using Dal.CA