[MacPorts] #65623: ffmpeg: update to 6.x

[MacPorts]

#65623: ffmpeg: update to 6.x
-------------------------+----------------------
  Reporter:  janngobble  |      Owner:  mascguy
      Type:  update      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.7.2
Resolution:              |   Keywords:
      Port:  ffmpeg      |
-------------------------+----------------------

Comment (by mascguy):

 Replying to [comment:17 mascguy]:
 > > How would one use ffmpeg6 or (the eventual) ffmpeg4 in a port? Is it a
 matter of updating `configure.cppflags` and `configure.ldflags`?
 >
 > Hopefully most can be updated to include the `pkgconfig` path for the
 desired version of `ffmpeg`, via logic similar to the following:
 >
 > {{{
 > set ffmpeg_ver 6
 > configure.pkg_config_path
 ${prefix}/libexec/ffmpeg${ffmpeg_ver}/lib/pkgconfig
 > }}}

 p.s. To reduce the maintenance pain, I'm also planning to introduce a new
 `ffmpeg` portgroup - similar to our pg for `boost` - to ease the pain.
 That will also take time, but again, we'll get there.

-- 
Ticket URL: <https://trac.macports.org/ticket/65623#comment:18>
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