bug#12642: Incorrect information in online manual

[Oscar Tobar]

According to 
http://www.gnu.org/software/coreutils/manual/html_node/Block-size.html the 
environment variable POSIXLY_CORRECT sets the block size of ls to 512 in 
certain cases. This is not currently the case. The patch in which this behavior 
was disabled is 
http://lists.gnu.org/archive/html/bug-coreutils/2004-06/msg00050.html