PR libstdc++/85729
	* include/bits/c++config.h (__replacement_assert): Add linkage
	specification.
	* include/bits/std_abs.h: Add comment to closing brace of block.
	* include/c_global/cstddef: Add linkage specification.
	* include/c_global/cstring: Likewise.
	* include/c_global/cwchar: Likewise.

From-SVN: r260114