c: Update __has_c_attribute values for C2x

WG14 decided that __has_c_attribute should return the same value
(equal to the intended __STDC_VERSION__ value) for all standard
attributes in C2x, with values associated with when an attribute was
added to the working draft (or had semantics added or changed in the
working draft) only being used in earlier stages of development of
that draft.  The intent is that the values for existing attributes
increase in future standard versions only if there are new features /
semantic changes for those attributes.  Implement this change for GCC.

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

gcc/c-family/
	* c-lex.cc (c_common_has_attribute): Use 202311 as
	__has_c_attribute return for all C2x attributes.

gcc/testsuite/
	* gcc.dg/c2x-has-c-attribute-2.c: Expect 202311L return value from
	__has_c_attribute for all C2x attributes.

0 files changed, 0 insertions, 0 deletions