Before merging in the oss-fuzz corpora from Google, there are some changes
to the fuzzer.
- Add a read corpus script, to display corpus files nicely.
- Change the behaviour of the fuzzer so that TLV parse failures all now
  go down the same execution paths, which should reduce the size of the
  corpora.
- Make unknown TLVs a failure to parse, which should decrease the size
  of the corpora as well.

Closes #1881

... as it also removes a warning with old gcc versions.

Bug: https://curl.haxx.se/mail/lib-2017-09/0049.html
Reported-by: Ben Greear

Don't make the fuzzer write out to stdout - instead write some of the
contents to a memory block so we exercise the data output code but
quietly.

Closes #1885

... instead of truncating them.

There's no fixed limit for acceptable cookie names in RFC 6265, but the
entire cookie is said to be less than 4096 bytes (section 6.1). This is
also what browsers seem to implement.

We now allow max 5000 bytes cookie header. Max 4095 bytes length per
cookie name and value. Name + value together may not exceed 4096 bytes.

Added test 1151 to verify

Bug: https://curl.haxx.se/mail/lib-2017-09/0062.html
Reported-by: Kevin Smith

Closes #1894

- openssl is already installed and causes warnings when trying to
  install again

- libidn isn't used these days, and homebrew doesn't seem to have a
  libidn2 package to replace with easily

Closes #1895

... previously it would store a return value even when it returned
error, which could make the value get used anyway!

Reported-by: Brian Carpenter
Closes #1893

Prior to this change it appears the SOCKS5 port parsing was erroneously
used for the SOCKS4 error message, and as a result an incorrect port
would be shown in the error message.

Bug: https://github.com/curl/curl/issues/1892


Reported-by:  <Jackarain@users.noreply.github.com>

Schannel can only encrypt a certain amount of data at once.  Instead of
failing when too much data is to be sent at once, send as much data as
we can and let the caller send the remaining data by calling send again.

Bug: https://curl.haxx.se/mail/lib-2014-07/0033.html

Closes https://github.com/curl/curl/pull/1890

lib/vtls/openssl.c uses OpenSSL APIs from BUF_MEM and BIO APIs. Include
their headers directly rather than relying on other OpenSSL headers
including things.

Closes https://github.com/curl/curl/pull/1891

Bug: https://curl.haxx.se/mail/lib-2017-09/0031.html

If the INTERLEAVEFUNCTION is defined, then use that plus the
INTERLEAVEDATA information when writing RTP. Otherwise, use
WRITEFUNCTION and WRITEDATA.

Fixes #1880
Closes #1884

Closes https://github.com/curl/curl/pull/1687

The stub implementation is pre-loaded using LD_PRELOAD
and emulates common gssapi uses (only builds if curl is
initially built with gssapi support).

The initial tests are currently disabled for debug builds
as LD_PRELOAD is not used then.

Ref: https://github.com/curl/curl/pull/1687

Closes #1889

... as when a proxy connection is being re-used, it can still get a
different remote port.

Fixes #1887
Reported-by: Oli Kingshott

Closes #1878

... as the code style mandates.

... not only HTTP uses this now.

Closes #1875

CA path processing was implemented when mbedtls.c was added to libcurl
in fe7590f7, but it was never enabled.

Bug: https://github.com/curl/curl/issues/1877


Reported-by:  <SBKarr@users.noreply.github.com>

If the default write callback is used and no destination has been set, a
NULL pointer would be passed to fwrite()'s 4th argument.

OSS-fuzz bug https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3327
(not publicly open yet)

Detected by OSS-fuzz
Closes #1874

... to avoid a clang bug

Add support for HEADER, COOKIE, RANGE, CUSTOMREQUEST, MAIL_RECIPIENT,
MAIL_FROM and uploading data.

The tests for object file/executable file extensions are presumably only
done for the first of these macros in the configure file.

Bug: https://github.com/curl/curl/pull/1851#issuecomment-327597515
Reported-by: Marcel Raad
Closes #1873

Now that the form API is deprecated and not used anymore in curl tool,
a lot of its features left untested. Test 650 attempts to check all these
features not tested elsewhere.

- Prepend srcdir include path instead of append.

Prior to this change it was possible that during the check for the size
of curl_off_t the include path of a user's already installed curl could
come before the include path of the to-be-built curl, resulting in the
system.h of the former being incorrectly included for that check.

Closes https://github.com/curl/curl/pull/1870

It has already been fixed in 6140dfcf

`conn->connect_state` is NULL when doing a regular non-CONNECT request
over the proxy and should therefor be considered complete at once.

Fixes #1853
Closes #1862
Reported-by: Lawrence Wagerfield

Another mistake in my manual fixups of the largely mechanical
search-and-replace ("connssl->" -> "BACKEND->"), just like the previous
commit concerning HTTPS proxies (and hence not caught during my
earlier testing).

Fixes #1855
Closes #1871

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>