Исправление gag, (текущая версия) :
-lpthread
Только не так. А вот как в man gcc:
-pthread
Define additional macros required for using the POSIX threads library. You should use this option consistently for both compilation and linking.
This option is supported on GNU/Linux targets, most other Unix derivatives, and also on x86 Cygwin and MinGW targets.
Исходная версия gag, :
-lpthread
Только не так. А вот как в man gcc:
-pthread
Define additional macros required for using the POSIX threads library. You should use this option consistently for both compilation and linking.
This option is supported on GNU/Linux targets, most other Unix derivatives, and also on x86 Cygwin and MinGW targets.