config.gcc: Rework and simplfication

	* config.gcc (or1k*-*-*): Rework to share as much as
	possible across all targets.

Signed-off-by: Christian Svensson <blue@cmd.nu>
config/or1k/elf.h: Correct comment.

	* config/or1k/elf.h: Correct comment.

Signed-off-by: Christian Svensson <blue@cmd.nu>
Add or1k*-*-rtems* target

	* config/or1k/rtems.h: New file.
	* gcc/config/or1k/t-rtems: New file.
	* gcc/config.gcc (or1k*-*-rtems*): Add RTEMS support.

Signed-off-by: Christian Svensson <blue@cmd.nu>
Fix tab/space issue