Remove obsolete linker flag for Bebop build
Remove obsolete linker flag for Bebop build

The pthread linker flags were changed in c6a2641 and it was questioned in #5504 if the
exception for the Bebop is necessary. It is not, so remove those lines from the cmake
file.

mcgill-robotics/Firmware,acfloria/Firmware,Aerotenna/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,krbeverx/Firmware,dagar/Firmware,jlecoeur/Firmware,mje-nz/PX4-Firmware,jlecoeur/Firmware,PX4/Firmware,krbeverx/Firmware,jlecoeur/Firmware,acfloria/Firmware,Aerotenna/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,Aerotenna/Firmware,PX4/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,Aerotenna/Firmware,mje-nz/PX4-Firmware,acfloria/Firmware,dagar/Firmware,jlecoeur/Firmware,dagar/Firmware,dagar/Firmware,mcgill-robotics/Firmware,krbeverx/Firmware,Aerotenna/Firmware,PX4/Firmware,mcgill-robotics/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,Aerotenna/Firmware,Aerotenna/Firmware,mcgill-robotics/Firmware,mcgill-robotics/Firmware,dagar/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,PX4/Firmware,PX4/Firmware,mje-nz/PX4-Firmware