Fix libuv for <10.7

[barracuda156]

The patch fixes the build on older MacOS and is based on Macports one: https://github.com/macports/macports-ports/blob/master/devel/libuv/files/patch-libuv-legacy.diff

[barracuda156]

Ubuntu check failure looks unrelated:

── R CMD check results ────────────────────────────────────── fs 1.5.2.9000 ────
Duration: 1m 5.6s

❯ checking compiled code ... WARNING
  File ‘fs/libs/fs.so’:
    Found ‘__sprintf_chk’, possibly from ‘sprintf’ (C)
      Object: ‘file.o’
  
  Compiled code should not call entry points which might terminate R nor
  write to stdout/stderr instead of to the console, nor use Fortran I/O
  nor system RNGs nor [v]sprintf.
  
  See ‘Writing portable packages’ in the ‘Writing R Extensions’ manual.

❯ checking for GNU extensions in Makefiles ... NOTE
  GNU make is a SystemRequirements.

0 errors ✔ | 1 warning ✖ | 1 note ✖
Error: Error: R CMD check found WARNINGs
Execution halted
Error: Process completed with exit code 1.