cris: Parenthesize parameter to as_a.

cris: Parenthesize parameter to as_a.

Noted by Richard Sandiford in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103974#c7 (thanks!)

Mea culpa: I wrongly thought the default development-level value
("yes,extra") would include everything interesting to normal target
hacking (i.e. as opposed to hacking stuff like GC).  I see
rtl-checking is marked as "expensive" and presumably therefore left
out.  Maybe it could be split into rtl-static (cheap; catching type
errors including this kind of foulups) and rtl-dynamic (the expensive
parts).  I suppose that's for whomever feels a strong enough itch.

A quick (error-prone) grep-and-eyeball in config/ shows this was the
only file missing the parenthesis.  This lets cris-elf configured with
--enable-checking=yes,extra,rtl survive make all-gcc.

2022-01-11  Hans-Peter Nilsson  <hp@axis.com>

	* config/cris/cris.c (cris_postdbr_cmpelim): Parenthesize
	parameter to as_a.