sysdeps: Don't raise RLIMIT_NOFILE beyond OPEN_MAX on macOS

dbus-daemon fails to launch on macOS 10.5 and above because of a breaking
change in setrlimit, in which RLIM_INFINITY is no longer supported
for RLIMIT_NOFILE. Instead we must use OPEN_MAX.

Resolves: #309
11 jobs for macos-setrlimit-bugfix in 9 minutes and 4 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #5449400
build:cmake

00:03:59

passed #5449397
build:debug

00:08:04

manual #5449402
allowed to fail manual
build:i686-w64-mingw32-cmake
passed #5449401
build:i686-w64-mingw32-debug

00:05:15

manual #5449399
allowed to fail manual
build:legacy
passed #5449396
build:production

00:05:32

manual #5449398
allowed to fail manual
build:reduced
manual #5449405
allowed to fail manual
build:stretch
passed #5449403
build:x86_64-w64-mingw32

00:04:27

passed #5449404
build:x86_64-w64-mingw32-cmake-debug

00:09:01

manual #5449406
allowed to fail manual
build:xenial