[MacPorts] #64675: fix libvpx for PowerPC and update ffmpeg accordingly

[MacPorts]

#64675: fix libvpx for PowerPC and update ffmpeg accordingly
------------------------------+----------------------------
 Reporter:  barracuda156      |      Owner:  (none)
     Type:  enhancement       |     Status:  new
 Priority:  Normal            |  Milestone:
Component:  ports             |    Version:  2.7.1
 Keywords:  powerpc, leopard  |       Port:  libvpx, ffmpeg
------------------------------+----------------------------
 I open a new ticket referring from here:
 https://trac.macports.org/ticket/64653

 So far I have been able to fix `libvpx` 1.5.0 and 1.6.1 to build for
 PowerPC.

 {{{
 36-47:~ svacchanda$ port -v installed libvpx
 The following ports are currently installed:
   libvpx @1.6.1_0 (active) requested_variants='-universal'
 platform='darwin 9' archs='ppc' date='2022-02-16T21:07:00+0800'
 }}}

 It is quite probable later versions will build too, even though starting
 from 1.7.0 identical fixes fail to work (possibly introduction of
 powerpc64le there messes things up).
 I will still try to fix the latest `libvpx` for PowerPC and update here
 once/if that succeeds.

 `ffmpeg` port file can be updated, as now it has:

 {{{
     # as of 1.6.0 libvpx only supports darwin 10 or later
     if {${os.major} < 10} {
         depends_lib-delete path:lib/pkgconfig/vpx.pc:libvpx
         configure.args-replace --enable-libvpx --disable-libvpx
     }
 }}}

 However 1.6.1 already builds on 10.5.8 (and 10.6 PPC too).

-- 
Ticket URL: <https://trac.macports.org/ticket/64675>
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