tree-wide: no need to pass excess flags to open()/openat() if O_PATH is passed

As described in the documentation:

When O_PATH is specified in flags, flag bits other than O_CLOEXEC,
O_DIRECTORY, and O_NOFOLLOW are ignored.

So, we can remove unnecessary flags in a case when O_PATH is passed
to the open() or openat().

src/basic/xattr-util.c

@@ -110,7 +110,7 @@ ssize_t fgetxattrat_fake(int dirfd, const char *filename, const char *attribute,
 
         /* The kernel doesn't have a fgetxattrat() command, hence let's emulate one */
 
-        fd = openat(dirfd, filename, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
+        fd = openat(dirfd, filename, O_CLOEXEC|O_PATH|(flags & AT_SYMLINK_NOFOLLOW ? O_NOFOLLOW : 0));
         if (fd < 0)
                 return -errno;