Add counter-cases for trace-condition.exp tests

Add counter-cases for trace-condition.exp tests

In trace-condition.exp, tests are done by doing a conditional tracepoint
and validating that the trace contains all the frames that could be
collected if that condition is true.

E.g. test_tracepoints $trace_command "21 + 21 == 42" 10

This will always return true and collect the 10 frames possible to collect
with the test program.

However, if the condition evaluation is broken such that the condition is
unconditional we will not notice this problem.

This patch adds counter-cases to such conditions like so:

$trace_command "21 + 11 == 42" 0

This way such a problem would be noticed.

gdb/testsuite/ChangeLog:

	* gdb.trace/trace-condition.exp: Add counter-case tests.