* arm.cc: Added support for ARM group relocations.
(Target_arm::reloc_needs_sym_origin): New method.
(Arm_relocate_functions::calc_grp_kn): New method.
(Arm_relocate_functions::calc_grp_residual): New method.
(Arm_relocate_functions::calc_grp_gn): New method.
(Arm_relocate_functions::arm_grp_alu): New Method.
(Arm_relocate_functions::arm_grp_ldr): New Method.
(Arm_relocate_functions::arm_grp_ldrs): New Method.
(Arm_relocate_functions::arm_grp_ldc): New Method.
(Target_arm::Scan::local): Handle the ARM group relocations.
(Target_arm::Scan::global): Likewise.
(Target_arm::Relocate::relocate): Likewise.
(Target_arm::Relocatable_size_for_reloc::get_size_for_reloc):
Likewise.