This patch removes completely the support for the program section, the
parsing of the section as well as the internals in the mworker does not
support it anymore.
The program section was considered dysfonctional and not fully
compatible with the "mworker V3" model. Users that want to run an
external program must use their init system.
The documentation is cleaned up in another patch.
Here, to distinguish between the new worker and the previous one let's add a
new process state PROC_O_INIT and let's set it, when the memory is allocated
for the new worker in the processes list.
Implement a reload failure counter which counts the number of failure
since the last success. This counter is available in 'show proc' over
the master CLI.
The relative_pid is always 1. In mworker mode we also have a
child->relative_pid which is always equalt relative_pid, except for a
master (0) or external process (-1), but these types are usually tested
for, except for one place that was amended to carefully check for the
PROC_O_TYPE_WORKER option.
Changes were pretty limited as most usages of relative_pid were for
designating a process in stats output and peers protocol.
One function prototype makes reference to struct mworker_proc which was
not defined there but in global.h instead. This definition, along with
the PROC_O_* fields were moved to mworker-t.h instead.
