* bfd/cofflink.c (_bfd_coff_generic_relocate_section): Resolve PE weak
externals properly.
* src/gas/config/obj-coff.c (obj_coff_weak): New .weak syntax for PE weak
externals.
* binutils/doc/binutils.texi (nm): Clarify weak symbol description.
* gas/config/tc-i386.c (tc_gen_reloc): Use addend for weak symbols in TE_PE.
* gas/doc/as.texinfo (Weak): Document PE weak symbols.
* ld/ld.texinfo (WIN32): Document PE weak symbols.