tool: Fixed libcurl source output for multiple operations

Correctly output libcurl source code that includes multiply operations
as specified by --next. Note that each operation evaluates to a single
curl_easy_perform() in source code form.

Also note that the output could be optimised a little so global config
options are only output once rather than per operation as is presently
the case.
tool: Do not output libcurl source for the information only parameters

Ensure a source file isn't generated for the following informational
command line parameters when --libcurl is specified:

--help, --manual, --version and --engine list

As the output would only include a fairly empty looking main() function
and a call to curl_easy_init() and curl_easy_cleanup() when performed
with --engine list.
RELEASE-NOTES: Synced with 7fef4016de
parsedate: Fixed compilation warning

Remove compilation message for platforms where size of long type
is equal size of int type.