Fix comparison of integers with the bool type in test cases for the Trie class.

This commit fixes comparisons of different types when checking the
return values of `trie.findValue()` in the test cases in testFind().
In test cases in testErase(), the return values of that function are
correctly checked with the binary operation "!=".
Merge pull request #4 from tetsuok/fix-trie-main-test

Fix comparison of integers with the bool type in test cases for the Trie class