[MacPorts] #47299: Update Xcode on buildbot builders

[MacPorts]

#47299: Update Xcode on buildbot builders
-----------------------------+---------------------
  Reporter:  ryandesign@…    |      Owner:  admin@…
      Type:  enhancement     |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:                  |
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Comment (by mojca@…):

 The original problem was reported in #47273, this was the particular
 failed build:
 - https://build.macports.org/builders/buildports-mtln-x86_64/builds/22269

 If you check `compile -> stdio` logs from "any given" build on the
 Mountain Lion buildbot, you'll see the following line:
 {{{
 DEBUG: compiler clang 421.11.66 not blacklisted because it doesn't match
 {clang < 211.10.1}
 }}}
 while it's OK on Lion:
 {{{
 DEBUG: compiler clang 425.0.28 not blacklisted because it doesn't match
 {clang < 211.10.1}
 }}}
 This was confirmed after I blacklisted clang < 425, the buildbot used
 `macports-clang-3.4` and the build succeeded. On Lion the "native"
 compiler was used.

 An up-to-date Xcode and outdated command line tools would be a valid
 explanation for this situation.

-- 
Ticket URL: <https://trac.macports.org/ticket/47299#comment:2>
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