[PATCH] libstdc++/8399

[David Edelsohn]

	This patch causes a bootstrap failure on AIX:

/gcc/dje/src/libstdc++-v3/src/ios.cc: In static member function `static void std::ios_base::Init::_S_ios_create(bool)':
/gcc/dje/src/libstdc++-v3/src/ios.cc:161: error: `isatty' undeclared (first use this function)
/gcc/dje/src/libstdc++-v3/src/ios.cc:161: error: (Each undeclared identifier is reported only once for each function it appears in.)

	Where is <unistd.h> included in libstdc++/src/ios.cc ?

David