Change error and fatal messages to start with lowercase and not
end with a period. Note a few very common messages were left
as-is, just in case some other tools parse them.
Also modify the test known-good-output to satisfy the messages.
The GNU platform testers reported a number of test errors on
different systems; try to address them.
* tests/thelp.pl: A number of tests timed out with a 4-second
timeout. Increase the default timeout to 10 seconds.
* tests/run_make_tests.pl: Executing directories on cygwin behaves
differently in Perl than make so skip these tests there.
* tests/scripts/options/symlinks: Check for the symlink feature
in make, rather than whether the system supports them.
* tests/scripts/features/implicit_search: On some systems "false"
exits with a different exit code. Use the helper instead.
* tests/scripts/features/loadapi: Ditto.
* tests/scripts/features/output-sync: Sleep before make -f bar in
the first test as well as the second one.
* tests/scripts/features/exec: Skip on cygwin, which seems to
be "UNIX" but where scripts don't run normally.
* tests/scripts/misc/fopen-fail: Skip on cygwin, where make
eventually exits with exit code 0 and no error messages.
If a prereq of a pattern is explicitly mentioned as a prereq of an
unrelated rule, it should not be considered an intermediate file.
* tests/scripts/features/double_colon: Add tests mentioning unrelated
explicit targets.
* tests/scripts/features/grouped_targets: Ditto.
* tests/scripts/features/implicit_search: Ditto.
* tests/scripts/features/patternrules: Ditto.
* tests/scripts/features/se_implicit: Ditto.
* tests/scripts/features/statipattrules: Ditto.
Target-specific variables used to define the target as "ought to
exist" so they could never be intermediate. Now they can be, so
merge the target-specific variables from the intermediate target
so they're not lost.
* src/implicit.c (pattern_search): Use merge_variable_set_lists
to merge target-specific variables.
* tests/scripts/features/implicit_search: Add tests of target-
specific variable assignments and implicit rules.
The traditional definition of "ought to exist" in the user's manual can
lead to make choosing a poor series of chained implicit rules. Modify
that rule so that we first attempt to resolve implicit rules by
considering targets which are only (a) targets or (b) explicit
prerequisites of the current target.
For backward-compatibility, if we don't find a solution using that
algorithm use the previous definition where "ought to exist" means
"mentioned as a prerequisite of any target".
* src/implicit.c (pattern_search): An extra argument controls whether
to perform the backward-compatible rule search or not. If a prereq is
a target, or if it's a prerequisite of THIS target, then choose it.
If we get to the end and haven't found a match, but we have found a
potential compatibility rule, then retry with compat rules enabled.
If we're searching with compat rules enabled and we find a file
mentioned as a prerequisite of ANY target, then use it.
* tests/features/implicit_search: Provide a large suite of tests for
different steps of implicit rule search.
