cmake: remove unneeded file build_git_version.h.in
cmake: remove unneeded file build_git_version.h.in

Obsolete since 9ee478e1f75a3b2355a8ce84d87d5f16055ac2f6

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