make: unify debug messages for parallel mode

Always print the process status in hex, with a leading "0x", to avoid
confusion for status 127f, which looks suspiciously decimal.

Prefix all process IDs with "pid", to be able to filter them easily.

Omit trailing whitespace when printing a command.

make: replace magic numbers in job debug log with descriptive names

make: use uniform debug log messages for the token pool

make: in the debug log, replace magic numbers with identifiers

make: group the code for handling the job token pool

branches: 1.10.8;
make(1): move Job.xtraced to ShellWriter

This flag was placed wrong in the Job since it is only necessary as long
as the shell commands are written to the shell file.

Resetting it in JobStart and JobExec was completely misguided since that
is far away from writing the shell commands; this should have been done
in JobPrintCommands instead.

The status of this flag doesn't need to be printed in debugging mode
since it is controlled by a single command line option (-dx) and does
not interact with all the other switches.

make(1): split JobFlags into separate fields

Having all these flags in a single bitmask makes it harder to see where
exactly they can possibly be used since their state could also be
modified using the unsuspicious job->flags = 0. Using individual names
just leaves the single memset, and that is only used during
initialization.

make(1): fix test opt-debug-jobs when compiled with dash as shell

make USER_CPPFLAGS=-DDEFSHELL_CUSTOM='\"/usr/pkg/bin/dash\"'

make(1): avoid race condition in test opt-debug-jobs

Thanks sjg for finding this and suggesting the fix.

make(1): clean up debug output for running jobs

There is no remote anymore, therefore mentioning locally is redundant.
It was a bad idea anyway to build format strings that work with parts of
words.

make(1): fix test opt-debug-jobs on non-native platforms

make(1): revert previous commit

It had accidentally reverted all the work from the past few days.

make(1): fix double-free bug in -DCLEANUP mode (since 2020-10-02)

The bug had been introduced with dir.c 1.155 on 2020-10-02 22:20:25. In
that commit, openDirectories was replaced with a combination of a list
with a hash table, for more efficient lookup by name.

Upon cleanup, OpenDirs_Done is called, which in turn called
Dir_ClearPath. Dir_ClearPath takes full ownership of the given list and
empties it. This was no problem before since afterwards the list was
empty and calling Lst_Free just frees the remaining list pointer.

With OpenDirs, this list was combined with a hash table, and the hash
table contains the list nodes, assuming that the OpenDirs functions have
full ownership of both the list and the hash table. This assumption was
generally correct, except for the one moment during cleanup where full
ownership of the list was passed to Dir_ClearPath, while the hash table
still contained pointers to the (now freed) list nodes. This by itself
was not a problem since the hash table would be freed afterwards. But
as part of Dir_ClearPath, OpenDirs_Remove was called, which looked up
the freed directory by name and now found the freed list node, trying to
free it again. Boom.

Fixed by replacing the call to Dir_ClearPath with code that only frees
the directories, without giving up control over the list.

make(1): add test for the -dj debug option

make(1): add tests for each debug option