[Lazarus] Cannot find -lpthread

["Leonardo M. Ramé"]

Hi, I'm trying to build fpc and lazarus from sources in XUbuntu 14.04. 
While trying to link fpc I get this:

/usr/bin/ld: aviso: link.res contiene secciones de salida. ¿Olvidó -T?
/usr/bin/ld: no se puede encontrar -lpthread
/usr/bin/ld: no se puede encontrar -ldl
/usr/bin/ld: no se puede encontrar -lc
fpmake.pp(44,1) Error: Error while linking

Does anyone know which package I'm missing? I've installed 
build-essential and libpthread-stubs0, but it still cannot find pthread...

Regards,
-- 
Leonardo M. Ramé
http://leonardorame.blogspot.com