We need some eCos tests to qualify specific features, particular GDB
features, during QA. By extending the QA process with tests written
specifically for interactive testing, we should get a better (and more
consistent) cover of features that may otherwise only get tested by
chance.

 o GDB single stepping
    - test s / n commands  (series of functions calling each other)
    - test bt when at bottom of call chain
    - test si / ni commands
    - test the scheduler-lock GDB/stub feature [this one is hard]

 o Selective linking
    - Build test with known-dead function in. Use objdump/nm to ensure
      it's been nuked. Same for .data, .rodata, and .bss objects.