To make uploads significantly faster in some circumstances.

Part 2 of #2888
Closes #2892

Saves 16KB on the easy handle for operations that don't need that
buffer.

Part 1 of #2888

Handles created with curl_easy_duphandle do not use the SSL engine set
up in the original handle. This fixes the issue by storing the engine
name in the internal url state and setting the engine from its name
inside curl_easy_duphandle.

Reported-by: Anton Gerasimov
Signed-of-by: Laurent Bonnans
Fixes #2829
Closes #2833

If this is the last stream on this connection, the RST_STREAM might not
get pushed to the wire otherwise.

Fixes #2882
Closes #2887
Researched-by: Michael Kaufmann

Follow-up to 099f37e9

Pointed-out-by: Marcel Raad

This struct field is never set TRUE in any existing code path. This
change removes the field completely.

Closes #2871

... simply because this is usually a sign of the user having omitted the
file name and the next option is instead "eaten" by the parser as a file
name.

Add test1268 to verify

Closes #2885

Might help bug #2688 debugging

Closes #2880

... since the gcc-8 ones seem to fail frequently.

Follow-up from b8520719

Closes #2886

... and now listed in alphabetical order!

This change allows to use the CMake config files generated by Curl's
CMake scripts for static builds of the library.
The symbol CURL_STATIC lib must be defined to compile downstream,
thus the config package is the perfect place to do so.

Fixes #2817
Closes #2823
Reported-by: adnn on github
Reviewed-by: Sergei Nikulov

Added test 656 (based on test 604) to verify the fix.

Bug: https://bugzilla.redhat.com/1595135

Closes #2879

The verbose message "Authentication using SSH public key file" was
printed each time the ssh_userauth_publickey_auto() was called, which
meant each time a packet was transferred over network because the API
operates in non-blocking mode.

This patch makes sure that the verbose message is printed just once
(when the authentication state is entered by the SSH state machine).

Since they started to fail almost 100% since a few days.

Closes #2876

Closes https://github.com/curl/curl/pull/2869

Deal with tiny "HTTP/0.9" (header-less) responses by checking the
status-line early, even before a full "HTTP/" is received to allow
detecting 0.9 properly.

Test 1266 and 1267 added to verify.

Fixes #2420
Closes #2872

... to make make the files appear in distribution tarballs

Closes #2856

... when curl is built from distribution tarball

Closes #2856

Split off testing file names with double quotes into new test 1158.
Disable it for MSYS using a precheck as it doesn't support file names
with double quotes (but Cygwin does, for example).

Fixes https://github.com/curl/curl/issues/2796
Closes https://github.com/curl/curl/pull/2854

- Determine if perl is in the user's PATH by running perl.exe.

Prior to this change detection was done by checking the PATH for perl/
but that did not work in all cases (eg git install includes perl but
not in perl/ path).

Bug: https://github.com/curl/curl/pull/2865
Reported-by: Daniel Jeliński

- CURLOPT_HEADERFUNCTION: add newlines
- CURLOPT_INTERLEAVEFUNCTION: fix the description of 'userdata'
- CURLOPT_READDATA: mention crashes, same as in CURLOPT_WRITEDATA
- CURLOPT_READFUNCTION: rename 'instream' to 'userdata' and explain
  how to set it

Closes https://github.com/curl/curl/pull/2868

Pointed-out-by: Rikard Falkeborn
Closes https://github.com/curl/curl/pull/2860

On Windows, casting between unrelated function types is fine and
sometimes even necessary, so just use an intermediate cast to
(void (*) (void)) to silence the warning as described in [0].

[0] https://gcc.gnu.org/onlinedocs/gcc-8.1.0/gcc/Warning-Options.html

Closes https://github.com/curl/curl/pull/2860

Adds test 1522 for verification.

Reported-by: cjmsoregan
Fixes #2847
Closes #2864

Closes #2867

Follow-up to 298d2565
Coverity CID 1438387

Follow-up to 2de63ab1 and
0b87c963.

Closes https://github.com/curl/curl/pull/2862

Reported-by: Marcel Raad
Fixes #2861
Closes #2863

Fixes #2837
Closes #2858
Reported-by: Markus Elfring

Closes #2857

Previously, the macro TEST_HANG_TIMEOUT was unused, but since there is
looping going on, we might as well add timing instead of removing it.

Closes #2853

The macro has never been used, and it there is not really any place
where it would make sense to add timing checks.

Closes #2852

The macro seems to never have been used.

Closes #2852

Usage was removed in 5113ad04.

Closes #2852

Its usage was removed in
84ad1fd3.

Closes #2852

Their usage was removed in 3a145180.

Closes #2852

Fixes #2806
Closes #2843

... by making sure it uses the -I provided by pkg-config!

Reported-by: pszemus on github
Fixes #2848
Closes #2850