Change getattr and statx to bespoke policies

* Provides: slight improvement in performance as it no longer will
need to find and then act on the files.
* It doesn't make sense to support all original policy types. Most
people used 'newest' or 'ff' and 'combine' is a better default which
has same runtime as 'newest' but with better output.

src/func_getxattr_ff.cpp

@@ -0,0 +1,35 @@
+#include "func_getxattr_ff.hpp"
+
+#include "error.hpp"
+#include "fs_lgetxattr.hpp"
+
+
+std::string_view
+Func2::GetxattrFF::name() const
+{
+  return "ff";
+}
+
+int
+Func2::GetxattrFF::operator()(const Branches &branches_,
+                              const fs::path &fusepath_,
+                              const char     *attrname_,
+                              char           *attrval_,
+                              const size_t    attrvalsize_)
+{
+  int rv;
+  Err err;
+  fs::path fullpath;
+
+  for(const auto &branch : branches_)
+    {
+      fullpath = branch.path / fusepath_;
+
+      rv = fs::lgetxattr(fullpath,attrname_,attrval_,attrvalsize_);
+      if(rv >= 0)
+        return rv;
+      err = rv;
+    }
+
+  return err;
+}