PR libstdc++/81706
* attribs.c (attribute_value_equal): Use omp_declare_simd_clauses_equal
for comparison of OMP_CLAUSEs regardless of flag_openmp{,_simd}.
(duplicate_one_attribute, copy_attributes_to_builtin): New functions.
* attribs.h (duplicate_one_attribute, copy_attributes_to_builtin): New
declarations.
* c-decl.c (merge_decls): Copy "omp declare simd" attributes from
newdecl to corresponding __builtin_ if any.
* decl.c (duplicate_decls): Copy "omp declare simd" attributes from
newdecl to corresponding __builtin_ if any.
* gcc.target/i386/pr81706.c: New test.
* g++.dg/ext/pr81706.C: New test.
From-SVN: r254069
