the 'missing path' test still works, but rather
accidentally: the plugin search path retrieved from
resolving $ORIGIN is an absolute path, while this
test uses relative paths; thus the querried plugin
won't be found. In the second test, we set an
environment override, using the relative path
(which is now 'modules'). Thus the discovery works.
test.h introduces a PLANNED_TEST() macro for C code, shows what tests
are provided and so on (the nobug version did that since some time).
test names are now passed as identifers and translated to strings by the
macros.
A lot fixes for existing tests, replace some printfs with ECHO, cosmetics.
one threadpool (sync_many) test is broken and set to PLANNED, this needs
further testsuite support for dispatching output.
add a TEST nobug flag to test.h
