* doc/extend.texi (Declaring Attributes of Functions): Correct
	typo for interrupt attribute. Note that branch-and-link has a
	21-bit offset.
	(ARC Built-in Functions): Use -mcpu=ARCv2EM
	throughout. Correct first argument of deftypefn in some places
	* doc/invoke.texi (ARC Options): Make clear that ARC v2 EM options
	are only available if built for ARC v2 EM. Add symbolic
	alternatives for -mmpy-option. Note that -medium-calls has a
	21-bit range. Clarify meaning of options passed through to the linker.