ltp: improve reproducibility

ltp package contains several gzipped files.
Improve reproducibility of the build by ensuring the gzipped files
do not contain timestamps in their headers.

https://wiki.debian.org/ReproducibleBuilds/TimestampsInGzipHeaders

(From OE-Core rev: d4ac52bef9f5364619fcb8e2f8c05927d660fff7)

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/ltp/ltp/0038-generate-reproducible-gzip.patch

@@ -0,0 +1,20 @@
+Do not generate timestamps in gzipped file headers.
+The timestamps prevent reproducible build.
+
+Upstream-Status: Submitted [https://github.com/linux-test-project/ltp/pull/233]
+
+Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
+
+diff --git a/testcases/network/generate.sh b/testcases/network/generate.sh
+index 00216a6..939f792 100755
+--- a/testcases/network/generate.sh
++++ b/testcases/network/generate.sh
+@@ -55,7 +55,7 @@ fi
+ if [ ! -e "bin.sm" ] ; then
+ 	cnt=0
+ 	while [ $cnt -lt 5 ] ; do
+-		gzip -1 -c ascii.sm >> "bin.sm"
++		gzip -1 -c -n ascii.sm >> "bin.sm"
+ 		cnt=$(($cnt + 1))
+ 	done
+ fi

meta/recipes-extended/ltp/ltp_20170929.bb

@@ -49,6 +49,7 @@ SRC_URI = "git://github.com/linux-test-project/ltp.git \
            file://0035-fix-test_proc_kill-hang.patch \
            file://0036-testcases-network-nfsv4-acl-acl1.c-Security-fix-on-s.patch \
            file://0037-ltp-fix-format-security-error.patch \
+           file://0038-generate-reproducible-gzip.patch \
            "
 
 S = "${WORKDIR}/git"