gmpc does not compile anymore

[krotalias]

gmpc does not compile on Catalina. It is just an implicit declaration, which is invalid in C99:

version:1 :debug:main Starting logging for gmpc @11.8.16_5 :debug:sysinfo macOS 10.15.7 (darwin/19.6.0) arch i386 :debug:sysinfo MacPorts 2.7.1 :debug:sysinfo Xcode 12.4 :debug:sysinfo SDK 10.15 :debug:sysinfo MACOSX_DEPLOYMENT_TARGET: 10.15

...................

:info:build Tools/gmpc-database-update-tracker.c:103:2: error: implicit declaration of function 'main_window_add_status_icon' is invalid in C99 [-Werror,-Wimplicit-function-declaration] :info:build main_window_add_status_icon ((GtkWidget*) self->priv->image); :info:build ^{:info:build 2 warnings generated.}