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/.stderrwithoutfirstline

@@ -5,5 +5,7 @@ warning: ..<...>/Input::READER_ASCII: Number '9223372036854775801TEXTHERE' conta
 warning: ..<...>/Input::READER_ASCII: Number '1Justtext' contained non-numeric trailing characters. Ignored trailing characters 'Justtext'
 warning: ..<...>/Input::READER_ASCII: String 'Justtext' contained no parseable number
 warning: ..<...>/Input::READER_ASCII: Could not convert line 'Justtext	1' of ../input.log to Val. Ignoring line.
+warning: ..<...>/Input::READER_ASCII: Number ' -18446744073709551612' cannot be negative
+warning: ..<...>/Input::READER_ASCII: Could not convert line '9223372036854775800	 -18446744073709551612' of ../input.log to Val. Ignoring line.
 received termination signal
 >>>

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]
 }