ARC e_flags vs. objcopy

ARC e_flags vs. objcopy

While the patch that Nick reverted in commit 3f6a060c7543 was in the
source, "FAIL: objcopy executable (pr25662)" was seen on ARC.  The
failure was triggered by the .ARC.attributes section being removed by
the linker script.  When a file lacking this section is copied by
objcopy, e_flags from the input is copied to the output (in this case
the value 0x406), but arc_elf_final_write_processing then logical-ors
in 0x300 when Tag_ARC_ABI_osver is not found.

	* elf32-arc.c (arc_elf_final_write_processing): Don't ignore
	existing e_flags for objcopy.