Add script for building xxHash

The code that requires xxHash requires a fairly new xxHash version, so
add a local copy of 0.8.0 to build with this header only library.

Signed-off-by: Arne Schwabe <arne@openvpn.net>

deps/lib-versions

@@ -22,4 +22,5 @@ export LZO_CSUM=c0f892943208266f9b6543b3ae308fab6284c5c90e627931446fb49b4221a072
 export OPENSSL_VERSION=openssl-1.1.1h
 export OPENSSL_CSUM=5c9ca8774bd7b03e5784f26ae9e9e6d749c9da2438545077e6b3d755a06595d9
 
-
+export XXHASH_VERSION=0.8.0
+export XXHASH_CSUM=7054c3ebd169c97b64a92d7b994ab63c70dd53a06974f1f630ab782c28db0f4f

deps/xxHash/build-xxHash

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+
+set -e
+if [ -z "$O3" ]; then
+    echo O3 var must point to ovpn3 tree
+    exit 1
+fi
+if [ -z "$DEP_DIR" ]; then
+    echo DEP_DIR var must point to dependency build folder
+    exit 1
+fi
+if [ -z "$DL" ]; then
+    echo DL var must point to the download folder
+    exit 1
+fi
+
+. $O3/core/deps/lib-versions
+
+# source helper functions
+. $O3/core/deps/functions.sh
+
+# https://github.com/Cyan4973/xxHash/archive/v0.8.0.tar.gz
+
+PACKAGE=${XXHASH_VERSION}
+FNAME=xxHash-${XXHASH_VERSION}.tar.gz
+URL=https://github.com/Cyan4973/xxHash/archive/v${XXHASH_VERSION}.tar.gz
+CSUM=${XXHASH_CSUM}
+DIST=xxHash
+
+download
+
+if [ "$NO_WIPE" = "1" ]; then
+    echo RETAIN existing source
+else
+    echo WIPE and reunzip source
+    cd $DEP_DIR
+    rm -rf $DIST xxHash-${XXHASH_VERSION}
+    tar xfz $DL/$FNAME
+    cd xxHash-${XXHASH_VERSION}
+
+    cd ..
+
+    cp -a xxHash-${XXHASH_VERSION} $DIST
+fi

scripts/linux/build-all

@@ -9,6 +9,8 @@ cd $DEP_DIR
 rm -rf asio* boost* lz4* lzo* minicrypto openssl* polarssl* snappy*
 echo "******* ASIO"
 $O3/core/deps/asio/build-asio
+echo "******* xxHash"
+$O3/core/deps/xxHash/build-xxHash
 echo "******* MBEDTLS"
 $O3/core/scripts/linux/build-mbedtls
 echo "******* LZ4"