make: make debug logging a bit more human-friendly

The previous log format "ParseReadLine (%d): '%s'" focused on the
implementation, it was not immediately obvious to a casual reader that
the number in parentheses was the line number. Additionally, having
both a colon and quotes in a log message is uncommon. The quotes have
been added in parse.c 1.127 from 2007-01-01.

The new log format "Parsing line %d: %s" is meant to be easier readable
by humans. The quotes are not needed since ParseReadLine always strips
trailing whitespace, leaving no room for ambiguities. The other log
messages follow common punctuation rules, which makes the beginning of
the line equally unambiguous. Before var.c 1.911 from 2021-04-05,
variable assignments were logged with the format "%s:%s = %s", without a
space after the colon.

make: remove filler word 'Do' from function names for parsing

No functional change, except for debug logging.

make(1): add more debugging for searching transformation rules

make(1): add explanation for test suff-rebuild

make(1): add more debug logging for suffix handling

One notable thing is that there is no debug output when adding a
transformation rule like ".c.o", which means that these rules don't end
up in the global allTargets variable.

This may or may not be intentional. It seems not intentional since this
is one of the causes for the suff-rebuild test to behave unexpectedly.

make(1): enable debug logging for test suff-rebuild

As long as it is not clear why this test fails, it's better to have the
debug log available, both for reading it and for getting notified if
any behavior in this area changes.

make(1): make output of test suff-rebuild more verbose

make(1): add test for deleting the suffixes during parsing

make: remove filler word 'Do' from function names for parsing

No functional change, except for debug logging.

make(1): add more debugging for searching transformation rules

make(1): add explanation for test suff-rebuild

make(1): add more debug logging for suffix handling

One notable thing is that there is no debug output when adding a
transformation rule like ".c.o", which means that these rules don't end
up in the global allTargets variable.

This may or may not be intentional. It seems not intentional since this
is one of the causes for the suff-rebuild test to behave unexpectedly.

make(1): enable debug logging for test suff-rebuild

As long as it is not clear why this test fails, it's better to have the
debug log available, both for reading it and for getting notified if
any behavior in this area changes.

make(1): make output of test suff-rebuild more verbose

make(1): add test for deleting the suffixes during parsing

make(1): add more debugging for searching transformation rules

make(1): add explanation for test suff-rebuild

make(1): add more debug logging for suffix handling

One notable thing is that there is no debug output when adding a
transformation rule like ".c.o", which means that these rules don't end
up in the global allTargets variable.

This may or may not be intentional. It seems not intentional since this
is one of the causes for the suff-rebuild test to behave unexpectedly.

make(1): enable debug logging for test suff-rebuild

As long as it is not clear why this test fails, it's better to have the
debug log available, both for reading it and for getting notified if
any behavior in this area changes.

make(1): make output of test suff-rebuild more verbose

make(1): add test for deleting the suffixes during parsing

make(1): add explanation for test suff-rebuild

make(1): add more debug logging for suffix handling

One notable thing is that there is no debug output when adding a
transformation rule like ".c.o", which means that these rules don't end
up in the global allTargets variable.

This may or may not be intentional. It seems not intentional since this
is one of the causes for the suff-rebuild test to behave unexpectedly.

make(1): enable debug logging for test suff-rebuild

As long as it is not clear why this test fails, it's better to have the
debug log available, both for reading it and for getting notified if
any behavior in this area changes.

make(1): make output of test suff-rebuild more verbose

make(1): add test for deleting the suffixes during parsing