It is still possible to override the executable to run during the test,
using the <tool> tag, but this patch removes the requirement that the
tag must be present for unit tests.
It also removes the possibility of human error when existing test cases
are used as the basis for new tests, as recently witnessed in 81c37124.
Reviewed-by: Daniel Stenberg
Closes#4976
This checks the new behavior of Curl_splaygetbest, so that the smallest
node not larger than the key is removed, and FIFO behavior is kept even
when there are multiple nodes with the same key.
Closes#1358
