ffmpeg, ffmpeg-devel, ffmpeg6: fix compilation problems with Xcode 15

[czo]

Description

Xcode 15 introduced a new linker, which is faster (said by Apple) but it cause some problems with existing software. Compiling ffmpeg port's cannot be done, because somewhere in the building process, multiple symbol exports are created with the same name, and the new linker cant link it. Apple introduced a new ldflag, which can bring back the old one, but this is a temporary solution, because this flag will be phased out in the future (date not disclosed yet).

Closes: https://trac.macports.org/ticket/68234

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 13.6 22G120 x86_64
Xcode 15.0 15A240d

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?

[macportsbot]

Notifying maintainers:
@mascguy for port ffmpeg-devel, ffmpeg, ffmpeg6.
@dbevans for port ffmpeg.
@jeremyhu for port ffmpeg.

[mascguy]

Looks good, will merge once CI completes.

Thank you for your contribution!

[Vargol]

Nevermind, forced a Command Line Tool re-install and it now works , even though though the clang version information is the same.

Leaving this here in case some one else has the same issue, re-install using,,,
https://trac.macports.org/wiki/ProblemHotlist#reinstall-clt

Hi, this pull has broken ffmpeg compiles for me.

/usr/bin/clang -I/opt/local/include -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -pipe -Os -DHAVE_LRINTF -Wno-deprecated-declarations -I/opt/local/include -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -arch arm64 -c -o /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_ffmpeg/ffmpeg/work/.tmp/ffconf.XZwEItEy/test.o /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_ffmpeg/ffmpeg/work/.tmp/ffconf.XZwEItEy/test.c
/usr/bin/clang -L/opt/local/lib -Wl,-headerpad_max_install_names -Wl,-ld_classic -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -arch arm64 -o /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_ffmpeg/ffmpeg/work/.tmp/ffconf.XZwEItEy/test /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_multimedia_ffmpeg/ffmpeg/work/.tmp/ffconf.XZwEItEy/test.o
ld: library not found for -ld_classic
clang: error: linker command failed with exit code 1 (use -v to see invocation)
C compiler test failed.

% /usr/bin/clang -v
Apple clang version 15.0.0 (clang-1500.0.40.1)
Target: arm64-apple-darwin23.0.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin