* aout-adobe.c (aout_32_bfd_define_common_symbol): Define.
	* aout-target.h (MY_bfd_define_common_symbol): Likewise.
	* aout-tic30.c (MY_bfd_define_common_symbol): Likewise.
	* binary.c (binary_bfd_define_common_symbol): Likewise.
	* bout.c (b_out_bfd_define_common_symbol): Likewise.
	* coff-alpha.c (_bfd_ecoff_bfd_define_common_symbol): Likewise.
	* coff-mips.c (_bfd_ecoff_bfd_define_common_symbol): Likewise.
	* coffcode.h (coff_bfd_define_common_symbol): Likewise.
	* elfxx-target.h (bfd_elfNN_bfd_define_common_symbol): Likewise.
	* i386msdos.c (msdos_bfd_define_common_symbol): Likewise.
	* i386os9k.c (os9k_bfd_define_common_symbol): Likewise.
	* ieee.c (ieee_bfd_define_common_symbol): Likewise.
	* ihex.c (ihex_bfd_define_common_symbol): Likewise.
	* libbfd-in.h (_bfd_nolink_bfd_define_common_symbol): Likewise.
	* mach-o.c (bfd_mach_o_bfd_define_common_symbol): Likewise.
	* mmo.c (mmo_bfd_define_common_symbol): Likewise.
	* nlm-target.h (nlm_bfd_define_common_symbol): Likewise.
	* oasys.c (oasys_bfd_define_common_symbol): Likewise.
	* pef.c (bfd_pef_bfd_define_common_symbol): Likewise.
	* ppcboot.c (ppcboot_bfd_define_common_symbol): Likewise.
	* som.c (som_bfd_define_common_symbol): Likewise.
	* srec.c (srec_bfd_define_common_symbol): Likewise.
	* tekhex.c (tekhex_bfd_define_common_symbol): Likewise.
	* versados.c (versados_bfd_define_common_symbol): Likewise.
	* vms.c (vms_bfd_define_common_symbol): Likewise.
	* xcoff-target.h (_bfd_xcoff_bfd_define_common_symbol): Likewise.
	* xsym.c (bfd_sym_bfd_define_common_symbol): Likewise.
	* coff-rs6000.c (rs6000coff_vec): Add _bfd_xcoff_define_common_symbol.
	(pmac_xcoff_vec): Likewise.
	* coff64-rs6000.c (rs6000coff64_vec): Likewise.
	(aix5coff64_vec): Likewise.
	* linker.c (bfd_generic_define_common_symbol): New function.
	* targets.c (BFD_JUMP_TABLE_LINK): Add NAME##_bfd_define_common_symbol.
	(_bfd_define_common_symbol): New field.
	* libcoff-in.h (_bfd_xcoff_define_common_symbol): Declare.
	* xcofflink.c (_bfd_xcoff_define_common_symbol): New function.
	(xcoff_build_ldsyms): Don't set XCOFF_DEF_REGULAR for common
	symbols here.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Likewise.
	* libcoff.h: Likewise.

ld/
	* ldlang.c (lang_one_common): Use bfd_define_common_symbol.

ld/testsuite/
	* ld-powerpc/aix-export-2.s, ld-powerpc/aix-export-2.nd: New test.
	* ld-powerpc/aix52.exp: Run it.