Fix bug in test filters where if you specified only a single test rather than a…

Fix bug in test filters where if you specified only a single test rather than a range, all tests after it in the same file would run.

c++/src/kj/test.c++

@@ -319,6 +319,7 @@ public:
           }
         } else if (*end == '\0') {
           parsedRange = true;
+          maxLine = minLine;
         }
       }