Pasale al compilador (que tiene que ser
gcc) el parametro -pthread o -lpthread, no se en ese IDE donde va pero debe ser facil de encontrar.
Segun este
Blog:
Select Build options...->Linker settings->add and add 'pthread' to Link libraries. Aca mas:
right click on the project name to the left, select Build options..., select Linker settings tab, click Add, then dig through the file system one by one for each shared library.
You can enter the names of the libs directly, instead of browsing the filesystem...
Just type the name of the lib in the popup dialog.
-pthread should be added to the other options both for compiler and linker.