rsync: fix CVEs for included zlib

rsync includes its own copy of zlib and doesn't recommend linking with
the system version [1].

Import CVE fixes that impact zlib version 1.2.8 [2] that is currently used
by rsync.

[1] https://git.samba.org/rsync.git/?p=rsync.git;a=blob;f=zlib/README.rsync
[2] https://nvd.nist.gov/vuln/search/results?form_type=Advanced&cves=on&cpe_version=cpe%3a%2fa%3agnu%3azlib%3a1.2.8

(From OE-Core rev: a55fbb4cb489853dfb0b4553f6e187c3f3633f48)

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/rsync/files/CVE-2016-9843.patch

@@ -0,0 +1,53 @@
+From d1d577490c15a0c6862473d7576352a9f18ef811 Mon Sep 17 00:00:00 2001
+From: Mark Adler <madler@alumni.caltech.edu>
+Date: Wed, 28 Sep 2016 20:20:25 -0700
+Subject: [PATCH] Avoid pre-decrement of pointer in big-endian CRC calculation.
+
+There was a small optimization for PowerPCs to pre-increment a
+pointer when accessing a word, instead of post-incrementing. This
+required prefacing the loop with a decrement of the pointer,
+possibly pointing before the object passed. This is not compliant
+with the C standard, for which decrementing a pointer before its
+allocated memory is undefined. When tested on a modern PowerPC
+with a modern compiler, the optimization no longer has any effect.
+Due to all that, and per the recommendation of a security audit of
+the zlib code by Trail of Bits and TrustInSoft, in support of the
+Mozilla Foundation, this "optimization" was removed, in order to
+avoid the possibility of undefined behavior.
+
+CVE: CVE-2016-9843
+Upstream-Status: Backport
+Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
+---
+ crc32.c | 4 +---
+ 1 file changed, 1 insertion(+), 3 deletions(-)
+
+diff --git a/zlib/crc32.c b/zlib/crc32.c
+index 979a7190..05733f4e 100644
+--- a/zlib/crc32.c
++++ b/zlib/crc32.c
+@@ -278,7 +278,7 @@ local unsigned long crc32_little(crc, buf, len)
+ }
+ 
+ /* ========================================================================= */
+-#define DOBIG4 c ^= *++buf4; \
++#define DOBIG4 c ^= *buf4++; \
+         c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \
+             crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24]
+ #define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4
+@@ -300,7 +300,6 @@ local unsigned long crc32_big(crc, buf, len)
+     }
+ 
+     buf4 = (const z_crc_t FAR *)(const void FAR *)buf;
+-    buf4--;
+     while (len >= 32) {
+         DOBIG32;
+         len -= 32;
+@@ -309,7 +308,6 @@ local unsigned long crc32_big(crc, buf, len)
+         DOBIG4;
+         len -= 4;
+     }
+-    buf4++;
+     buf = (const unsigned char FAR *)buf4;
+ 
+     if (len) do {