Added comment to sed using gcc.
Added comment to sed using gcc.

commented sed lline that makes "using gcc" as the default option for boost library
dacastro12/NTRT_Update,NASA-Tensegrity-Robotics-Toolkit/NTRTsim,NASA-Tensegrity-Robotics-Toolkit/NTRTsim,UnionEvoRobo/NTRTsim,MRNAS/NTRT,MRNAS/NTRT,dacastro12/NTRT_Update,NASA-Tensegrity-Robotics-Toolkit/NTRTsim,meshula/NTRTsim,MRNAS/NTRT,meshula/NTRTsim,NASA-Tensegrity-Robotics-Toolkit/NTRTsim,MRNAS/NTRT,dacastro12/NTRT_Update,dacastro12/NTRT_Update,UnionEvoRobo/NTRTsim,UnionEvoRobo/NTRTsim,UnionEvoRobo/NTRTsim,MRNAS/NTRT,dacastro12/NTRT_Update,meshula/NTRTsim,meshula/NTRTsim,NASA-Tensegrity-Robotics-Toolkit/NTRTsim,MRNAS/NTRT