httpd: don't allow tabs and multiple spaces in request string

HTTP standard doesn't allow it and no sane clients should ever use it.

function                                             old     new   delta
handle_incoming_and_exit                            2795    2785     -10

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
man: install to /usr/bin, not /sbin

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
hexdump: don't unconditionally limit the usable address range

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
hexdump: need to use xstrtoull for off_t

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Merge remote-tracking branch 'bb/master' into sm-jb-mr1