Skip negative integers in input framework where not type-permissible

Script-layer counts, when provided as negative integers in an input
file, got cast to unsigned values because strtoull() does not complain
about negative values. For example, input string "-1" would lead to
value 18446744073709551615 (an all-ones 64-bit int) on x86_64. This is
more likely to be an error than an intent to get very large,
platform-dependent values, so these input lines are now skipped with
according messaging in the reporter.log/stderr.

This also affected ports: -1/tcp got cast to unsigned and only thrown
out because PortVal rejects values > 65535, mapping them to 0. We now
skip such inputs as well.

Updates existing input framework tests to capture the new behavior.

testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/out

@@ -1,5 +1,4 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
 {
-[9223372036854775801] = [c=1],
-[9223372036854775800] = [c=4]
+[9223372036854775801] = [c=1]
 }