Fix handling of HTTP 1xx response codes (addresses #411).

Changed the parser to not treat 1xx response codes as a final answer
to an unanswered request -- a later response is still expected.

The scripting layer will also not finish a request-reply pair when
seeing 1xx's, instead it logs both the 1xx and final response messages
with associated information of the current request as they're seen.

testing/btest/scripts/base/protocols/http/100-continue.bro

@@ -0,0 +1,12 @@
+# This tests that the HTTP analyzer does not generate an unmatched_HTTP_reply
+# weird as a result of seeing both a 1xx response and the real response to
+# a given request.  The http scripts should also be able log such replies
+# in a way that correlates the final response with the request.
+#
+# @TEST-EXEC: bro -r $TRACES/http-100-continue.trace %INPUT
+# @TEST-EXEC: grep -q unmatched_HTTP_reply weird.log && exit 1 || exit 0
+# @TEST-EXEC: btest-diff http.log
+
+# The base analysis scripts are loaded by default.
+#@load base/protocols/http
+