Add C89-style parametric testing (RUN_TEST1).

While it isn't as nice as using __VA_ARGS__ in c99, it's still possible.
Don't hardcode the greatest_info struct literal, just use {0}.

It's statically allocated (should be zeroed), and we can check if
greatest_info.width has been changed to non-0 value before setting
it to the default. All other fields default to 0.
Bump version to 0.9.2 (mostly due to RUN_TEST1).