xcoff bfd.h tidy
    
    bfd/
    	* bfd-in.h: Move xcoff function declarations..
    	* xcofflink.h: ..to here, new file.
    	* xcofflink.c: Include xcofflink.h.
    	* coff-rs6000.c (bfd_xcoff_ar_archive_set_magic): Delete unused func.
    	* bfd-in2.h: Regenerate.
    ld/
    	* emultempl/aix.em: Include xcofflink.h.