The sub_config_and_use function recursed, but it also invoked
autowaf.set_local_lib , which however didn't do anything useful. The
HAVE_ defines are not used anywhere, and the AUTOWAF_LOCAL defines are
only used in autowaf.use_lib, which however isn't used anywhere.
Dropping these defines simplify the build environment and makes the
compiler command line half as long and thus makes debugging much more
manageable.
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