Makefile: fix misdirected redirections

In general "echo 2>&1 $msg" to redirect a possible error message that comes from 'echo' itself into the same standard output stream $msg is getting written to does not make any sense; it is not like we are expecting to see any errors out of 'echo' in these statements, and even if it were the case, there is no reason to prevent the error messages from being sent to the standard error stream. These are clearly meant to send the argument given to echo to the standard error stream as error messages. Correctly redirect by saying "send what is written to the standard output to the standard error", i.e. "1>&2" aka ">&2". Signed-off-by: Junio C Hamano <gitster@pobox.com>