Add c-deps as submodules

.gitmodules

@@ -1,3 +1,19 @@
 [submodule "github.com/facebook/rocksdb"]
 	path = c-deps/rocksdb
 	url = https://github.com/facebook/rocksdb.git
+[submodule "github.com/google/snappy"]
+	path = c-deps/snappy
+	url = https://github.com/google/snappy.git
+[submodule "github.com/lz4/lz4"]
+	path = c-deps/lz4
+	url = https://github.com/lz4/lz4.git
+[submodule "github.com/enthought/bzip2-1.0.6"]
+	path = c-deps/bzip2
+	url = https://github.com/enthought/bzip2-1.0.6.git
+[submodule "github.com/facebook/zstd"]
+	path = c-deps/zstd
+	url = https://github.com/facebook/zstd.git
+[submodule "github.com/madler/zlib"]
+	path = c-deps/zlib
+	url = https://github.com/madler/zlib.git
+

c-deps/gitsubmodules.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -e
+
+git config -f .gitmodules --get-regexp '^submodule\..*\.path$' |
+    while read path_key path
+    do
+        url_key=$(echo $path_key | sed 's/\.path/.url/')
+        url=$(git config -f .gitmodules --get "$url_key")
+        git submodule add $url $path
+    done