[MacPorts] #74236: rsync @3.4.1_0 fails to build on macOS 10.7

[MacPorts]

#74236: rsync @3.4.1_0 fails to build on macOS 10.7
----------------------------+------------------------
  Reporter:  scrutinizer11  |      Owner:  ryandesign
      Type:  defect         |     Status:  assigned
  Priority:  Normal         |  Milestone:
 Component:  ports          |    Version:  2.12.5
Resolution:                 |   Keywords:  lion
      Port:  rsync          |
----------------------------+------------------------

Comment (by fhgwright):

 The build fails on every OS earlier than 10.10, which is when the "at"
 calls were introduced.  It appears that some code intended to do without
 them isn't working as intended, e.g.
 [https://github.com/RsyncProject/rsync/pull/1026], and the "10.6" hack in
 [https://github.com/macports/macports-
 ports/blob/5cc1a1a2683838e63594592980821febb0b7b36a/net/rsync/Portfile#L61-L66]
 isn't really helping.

 The simplest fix may be just to start using `legacy-support` (which
 provides the "at" functions), with a maximum Darwin of 13, while removing
 the ineffective "10.6" hack.

-- 
Ticket URL: <https://trac.macports.org/ticket/74236#comment:4>
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