re PR libstdc++/89402 (warning: ‘void _ZNKSt4hashIeEclEe()’ specifies less restrictive attribute than its target)

	PR libstdc++/89402
	* src/c++98/compatibility-ldbl.cc (_ZNKSt4hashIeEclEe): Change return
	type to std::size_t and argument to type to long double.

From-SVN: r269130