Log texts also modified and some white space edits

Upgrade ILE/RPG binding to 7.21.7.
Update OS400 documentation accordingly.

We should probably also make sure that [protocol]_proxy for all possible
protocols libcurl supports are unset.

Bug: http://curl.haxx.se/mail/lib-2011-07/0074.html
Reported and fix suggested by: Ben Greear

gssapi.h is used as a header name by Heimdal-style GSSAPI so it would
conflict with a private header using that name, and while renaming the
header I figured we should name the .c file accordingly as well.

Bug: http://curl.haxx.se/mail/lib-2011-07/0071.html
Reported by: Ben Greear

Modern gcc versions (4.6.X) get more picky by default and have started
to warn for unused parameters, but luckily gcc also allows us to mark
them as unused so that we can avoid the warnings.

Removed the parameters that were common to all our invocation.

This function wraps our calls to gss_init_sec_context so that we
have a unified way to talk to GSSAPI.

This change makes this callsite match the rest of the code.

We use "if(condition) {" with a space between the close paren and the
open brace.

First, the -J/--remote-header-name was wrongly sorted in the --help
output as pointed out in bug report #3349271.

Then, I changed the format of the texts to follow the man page better in
that it now uses "-A, --long" intead of "-A/--long". I also made all
additional arguments get written as in "-A, --long FILENAME" instead of
the previous "<filename>" style.

Reported by: Herve Amblard
Bug: http://curl.haxx.se/bug/view.cgi?id=3349271

By default libcurl stops processing quote commands on failures.

Previously it would access a NULL pointer and die.

Bug: http://curl.haxx.se/mail/lib-2011-06/0170.html
Reported by: Christian Hagele

Only <curl/curl.h> is needed typically and curl/types.h has been removed

CURLM_CALL_MULTI_PERFORM stopped being a valid return code from
curl_multi_perform back in 7.20.0. All the libcurl tests are ajusted to
this and no longer check for this return code. Makes them simpler.

Autobuild submitters can use this to add some text to their
setup files to describe issues they've found with the build
or tests. This could include laying blame on test failures on
network issues or dependent libraries, explaining away compiler
warnings or providing any additional information that could be
useful to people reviewing and investigating problems with the
publicly available autobuild logs.  Note that persistent test
failures that are not issues with curl itself should normally be
fixed by excluding them from the test run instead.

This is an entirely optional field that is not entered by the
user the first time a new build is created.

Just to make sure a user is aware of it.

libcurl inappropriate GSSAPI delegation. Full details at
http://curl.haxx.se/docs/adv_20110623.html

This is a security flaw. See curl advisory 20110623 for details.

Reported by: Richard Silverman

[pop3] remove extra space in LIST command

Some servers, e.g. mail.bezeqint.net:110, consider it a syntax error

compiler warning: conditional expression is constant

compiler warning: variable is initialized but not referenced