POSIX says that suffix rules cannot have prerequisites, but after
making this change we observed a number of makefiles "in the wild"
that were relying on this behavior and failed.
For .POSIX: makefiles, obey POSIX. Otherwise preserve the old
behavior. However, generate a warning so users know this is a
problem. In a future version we will change all behavior to be
POSIX-conforming.
* NEWS: describe the change
* src/rule.c (convert_to_pattern): If posix_pedantic don't make a
pattern rule if prereqs exist. Otherwise show a warning.
* tests/scripts/features/suffixrules: Add tests for the new behavior
including .POSIX vs. non-.POSIX.
* NEWS: Update with a backward-compatibility warning.
* src/rule.c (convert_to_pattern): If a suffix rule has dependencies,
do not create a pattern rule for it. According to the manual suffix
rules with prerequisites are treated as normal targets.
* tests/scrips/features/suffixrules: Create some regression tests for
.SUFFIXES and suffix rules.
