apache: security bump to version 2.4.26

apache: security bump to version 2.4.26

Fixes the following security issues:

CVE-2017-3167: In Apache httpd 2.2.x before 2.2.33 and 2.4.x before 2.4.26,
use of the ap_get_basic_auth_pw() by third-party modules outside of the
authentication phase may lead to authentication requirements being bypassed.

CVE-2017-3169: In Apache httpd 2.2.x before 2.2.33 and 2.4.x before 2.4.26,
mod_ssl may dereference a NULL pointer when third-party modules call
ap_hook_process_connection() during an HTTP request to an HTTPS port.

CVE-2017-7659: A maliciously constructed HTTP/2 request could cause
mod_http2 to dereference a NULL pointer and crash the server process.

CVE-2017-7668: The HTTP strict parsing changes added in Apache httpd 2.2.32
and 2.4.24 introduced a bug in token list parsing, which allows
ap_find_token() to search past the end of its input string.  By maliciously
crafting a sequence of request headers, an attacker may be able to cause a
segmentation fault, or to force ap_find_token() to return an incorrect
value.

CVE-2017-7679: In Apache httpd 2.2.x before 2.2.33 and 2.4.x before 2.4.26,
mod_mime can read one byte past the end of a buffer when sending a malicious
Content-Type response header.

While we're at it, use the upstream sha256 checksum instead of sha1.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>