elf.c (ET_DYN): Undefine and define again.

	* elf.c (ET_DYN): Undefine and define again.
	(elf_add): Add exe argument, if true and ehdr.e_type is ET_DYN,
	return early -1 without closing the descriptor.
	(struct phdr_data): Add exe_descriptor.
	(phdr_callback): If pd->exe_descriptor is not -1, for very first
	call if dlpi_name is NULL just call elf_add with the exe_descriptor,
	otherwise backtrace_close the exe_descriptor if not -1.  Adjust
	call to elf_add.
	(backtrace_initialize): Adjust call to elf_add.  If it returns
	-1, set pd.exe_descriptor to descriptor, otherwise set it to -1.

From-SVN: r205748