PR ld/2754

	PR ld/2754
	* elf.c (bfd_elf_mkobject): Don't alloc if already done.  Set
	program_header_size to -1.
	(_bfd_elf_map_sections_to_segments): Adjust program_header_size check.
	(assign_file_positions_for_load_sections ): Likewise.
	(_bfd_elf_sizeof_headers): Use saved program_header_size if
	available.
	* elf32-arm.c (elf32_arm_mkobject): Call bfd_elf_mkobject, don't
	alloc if already done.
	* elf32-i386.c (elf_i386_mkobject): Likewise.
	* elf32-ppc.c (ppc_elf_mkobject): Likewise.
	* elf32-s390.c (elf_s390_mkobject): Likewise.
	* elf32-sh.c (sh_elf_mkobject): Likewise.
	* elf64-alpha.c (elf64_alpha_mkobject): Likewise.
	* elf64-ppc.c (ppc64_elf_mkobject): Likewise.
	* elf64-s390.c (elf_s390_mkobject): Likewise.
	* elf64-x86-64.c (elf64_x86_64_mkobject): Likewise.
	* elfxx-sparc.c (_bfd_sparc_elf_mkobject): Likewise.