When this define was set, libcurl would check the environment variable
named CURL_CA_BUNDLE at run-time and use that CA cert bundle. This
feature was only defined by the watcom and m32 makefiles and caused
inconsistent behaviours among libcurls built on different platforms.

The curl tool does already feature its own similar logic and the library
does not really need it, and it isn't documented libcurl behavior. So
this change removes it.

Ref: #1538

So many headers can be provided as @filename.

Suggested-by: Timothe Litt

Closes #1486

Mentioned as a problem since 2007 (8f87c15b) and of course it
existed even before that.

Closes #1547

Bug #1556
Reported-by: Paul Harris
Closes #1559

CURLSYS_PULL_WS2TCPIP_H got renamed to CURL_PULL_WS2TCPIP_H in commit
73a2fcea.

This gives us accurate precision and it allows us to avoid storing "no
time" for systems with too low timer resolution as we then bump the time
up to 1 microsecond. Should fix test 573 on windows.

Remove the now unused curlx_tvdiff_secs() function.

Maintains the external getinfo() API with using doubles.

Fixes #1531

The maketgz script now makes sure the generated hugehelp.c file in the
tarball is newer than the generated curl.1 man page, so that it doesn't
have to get unnecessarily rebuilt first thing in a typical build. It
thus also removes the need for perl to build off a plain release
tarball.

Fixes #1565

Rely entirely on curl/system.h now.

Introduced in Aug 2008 with commit 14240e9e. Now gone.

Fixes #1456

lib/vtls/openssl.c has a workaround for a bug with OCSP responses signed
by intermediate certs, this was fixed in LibreSSL in
https://github.com/libressl-portable/openbsd/commit/912c64f68f7ac4f225b7d1fdc8fbd43168912ba0

Bug: https://curl.haxx.se/mail/lib-2017-06/0038.html

Bug: https://github.com/curl/curl/issues/1540
Advisory: https://curl.haxx.se/docs/adv_20170614.html

Assisted-by: Ray Satiro
Reported-by: Marcel Raad

The multiply() function that is used to avoid integer overflows, was
itself reason for a possible division by zero error when passed a
specially formatted glob.

Reported-by: GwanYeong Kim

Don't malloc() the temporary buffer, and use the correct type:
SearchPath() works with TCHAR, but SearchPathA() works with char.
Set the buffer size to MAX_PATH, because the terminating null byte
is already included in MAX_PATH.

Reviewed-by: Daniel Stenberg
Reviewed-by: Marcel Raad

Closes #1548

Closes #1561

Reported-by: Marcel Raad
Bug: https://github.com/curl/curl/commit/cccac4fb2b20d6ed87da7978408c3ecacc464fe4#commitcomment-22453387

... and return error instead of triggering an assert() when being way
out of range.

Previously, one had to set MBEDTLS_INCLUDE_DIR to make CMake find the
headers, but the system complained that mbed TLS wasn't found due to
MBEDTLS_INCLUDE_DIRS (note the trailing s) was not set. This commit
attempts to fix that.

Closes https://github.com/curl/curl/pull/1541

Closes #1557

With the introduction of expire IDs and the fact that existing timers
can be removed now and thus never expire, the concept with adding a
"latest" timer is not working anymore as it risks to not expire at all.

So, to be certain the timers actually are in line and will expire, the
plain Curl_expire() needs to be used. The _latest() function was added
as a sort of shortcut in the past that's quite simply not necessary
anymore.

Follow-up to 31b39c40

Reported-by: Paul Harris

Closes #1555

Bug: https://curl.haxx.se/mail/lib-2017-06/0017.html

... as it would previously just get the "now" timestamp before the
transfer starts and then not update it again.

Closes #1550

typecheck-gcc and other things require optimized builds

Closes #1544

mk-lib1521.pl generates a test program (lib1521.c) that calls
curl_easy_setopt() for every known option with a few typical values to
make sure they work (ignoring the return codes).

Some small changes were necessary to avoid asserts and NULL accesses
when doing this.

The perl script needs to be manually rerun when we add new options.

Closes #1543

These error messages are not displayed with --disable-verbose