Update 'ring' to '0.16.17' (#368)

Cargo.lock

@@ -246,9 +246,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.0.60"
+version = "1.0.66"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef611cc68ff783f18535d77ddd080185275713d852c4f5cbb6122c462a7a825c"
+checksum = "4c0496836a84f8d0495758516b8621a622beb77c0fed418570e50764093ced48"
 
 [[package]]
 name = "cfg-if"
@@ -1018,9 +1018,9 @@ checksum = "8d3b63360ec3cb337817c2dbd47ab4a0f170d285d8e5a2064600f3def1402397"
 
 [[package]]
 name = "once_cell"
-version = "1.4.1"
+version = "1.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "260e51e7efe62b592207e9e13a68e43692a7a279171d6ba57abd208bf23645ad"
+checksum = "13bd41f508810a131401606d54ac32a467c97172d74ba7662562ebba5ad07fa0"
 
 [[package]]
 name = "opaque-debug"
@@ -1398,9 +1398,9 @@ dependencies = [
 
 [[package]]
 name = "ring"
-version = "0.16.15"
+version = "0.16.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "952cd6b98c85bbc30efa1ba5783b8abf12fec8b3287ffa52605b9432313e34e4"
+checksum = "c5911690c9b773bab7e657471afc207f3827b249a657241327e3544d79bcabdd"
 dependencies = [
  "cc",
  "libc",