mpd: fallback: support 10.15 and big sur

- Still more work necessary, for 10.14 and prior
See: https://trac.macports.org/ticket/65653

audio/mpd/Portfile

@@ -13,20 +13,32 @@ checksums           rmd160  45cc623a1029b010197a0233fe5ebb5f6e5fc5c4 \
                     sha256  86bb569bf3b519821f36f6bb5564e484e85d2564411b34b200fe2cd3a04e78cf \
                     size    773280
 
-set branch          [join [lrange [split ${version} .] 0 1] .]
 categories          audio
+license             GPL-2+ LGPL-2.1
 maintainers         nomaintainer
+
 description         Music Player Daemon
 long_description    Music Player Daemon (MPD) allows remote access for playing music \
     (MP3, Ogg Vorbis, FLAC, AAC, Mod, and wave files) and managing \
     playlists. MPD is designed for integrating a computer into a stereo \
     system that provides control for music playback over a local network. \
     It also makes a great desktop music player, especially if you are a \
     console junkie, like frontend options, or restart X often.
-
 homepage            https://www.musicpd.org/
+
+platform darwin {
+    if {${os.major} < 21} {
+        version     0.23.7
+        revision    2
+
+        checksums   rmd160  81749eef69fa544a88607f539519e3169dc152fe \
+                    sha256  960dcbac717c388f5dcc4fd945e3af19a476f2b15f367e9653d4c7a948768211 \
+                    size    771992
+    }
+}
+
+set branch          [join [lrange [split ${version} .] 0 1] .]
 master_sites        https://www.musicpd.org/download/${name}/${branch}/
-license             GPL-2+ LGPL-2.1
 use_xz              yes
 
 set python_branch   3.10