add zstd

zstd/build/single_file_libs/create_single_file_decoder.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+# Where to find the sources
+ZSTD_SRC_ROOT="../../lib"
+
+# Amalgamate the sources
+echo "Amalgamating files..."
+# Using the faster Python script if we have 3.8 or higher
+if python3 -c 'import sys; assert sys.version_info >= (3,8)' 2>/dev/null; then
+  ./combine.py -r "$ZSTD_SRC_ROOT" -x legacy/zstd_legacy.h -o zstddeclib.c zstddeclib-in.c
+else
+  ./combine.sh -r "$ZSTD_SRC_ROOT" -x legacy/zstd_legacy.h -o zstddeclib.c zstddeclib-in.c
+fi
+# Did combining work?
+if [ $? -ne 0 ]; then
+  echo "Combine script: FAILED"
+  exit 1
+fi
+echo "Combine script: PASSED"