ira: Fix `create_insn_allocnos' `outer' parameter documentation

The parameter of `create_insn_allocnos' for any parent expression of `x'
has always been called `outer' rather than `parent', just as added by
commit d1bb282efbf9 ("Fix for "FAIL: tmpdir-gcc.dg-struct-layout-1/t028
c_compat_x_tst.o compile, (internal compiler error)""),
<https://gcc.gnu.org/ml/gcc-patches/2014-09/msg02611.html>.  Correct
inline documentation accordingly.

	gcc/
	* ira-build.cc (create_insn_allocnos): Fix documentation.
1 file changed