* src/filesystem/ops.cc: Always include ostream and
ext/stdio_filebuf.h.
(do_copy_file): Check if _GLIBCXX_USE_FCHMODAT is defined.
[_GLIBCXX_USE_SENDFILE]: Fallback to read/write operations in case
sendfile fails with ENOSYS or EINVAL.
From-SVN: r239479
