POSIX: Make binutils BDF linker the default
POSIX: Make binutils BDF linker the default

ld.gold does not support the -Ur flags and it seems some people have
ld as a link to ld.gold.

Made LD = ld.bfd to avoid confusion.

Signed-off-by: Mark Charlebois <f1891e7fc976ae1bd489627e2954fb730751d728@gmail.com>

mje-nz/PX4-Firmware,acfloria/Firmware,acfloria/Firmware,jlecoeur/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,Aerotenna/Firmware,jlecoeur/Firmware,krbeverx/Firmware,darknight-007/Firmware,PX4/Firmware,PX4/Firmware,mje-nz/PX4-Firmware,dagar/Firmware,mcgill-robotics/Firmware,acfloria/Firmware,PX4/Firmware,Aerotenna/Firmware,mcgill-robotics/Firmware,mcgill-robotics/Firmware,dagar/Firmware,mje-nz/PX4-Firmware,Aerotenna/Firmware,Aerotenna/Firmware,darknight-007/Firmware,PX4/Firmware,dagar/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,jlecoeur/Firmware,mcgill-robotics/Firmware,jlecoeur/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,darknight-007/Firmware,krbeverx/Firmware,darknight-007/Firmware,krbeverx/Firmware,mje-nz/PX4-Firmware,darknight-007/Firmware,acfloria/Firmware,PX4/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,jlecoeur/Firmware,Aerotenna/Firmware,PX4/Firmware,krbeverx/Firmware,mcgill-robotics/Firmware,mcgill-robotics/Firmware,mje-nz/PX4-Firmware,krbeverx/Firmware,jlecoeur/Firmware,dagar/Firmware,acfloria/Firmware,acfloria/Firmware,Aerotenna/Firmware,Aerotenna/Firmware,dagar/Firmware,PX4/Firmware,acfloria/Firmware,dagar/Firmware