hide StdIoBackend behind backend-stdio feature

Signed-off-by: Laura Loghin <[email protected]>

Author: lauralt

Diff for: Cargo.toml

@@ -9,6 +9,9 @@ readme = "README.md"
 license = "Apache-2.0 OR MIT"
 edition = "2018"
 
+[features]
+backend-stdio = []
+
 [dependencies]
 byteorder = ">=1.2.1"
 libc = ">=0.2.39"

Diff for: coverage_config_aarch64.json

@@ -1,5 +1,5 @@
 {
   "coverage_score": 85.6,
   "exclude_path": "",
-  "crate_features": ""
+  "crate_features": "backend-stdio"
 }

Diff for: coverage_config_x86_64.json

@@ -1,5 +1,5 @@
 {
   "coverage_score": 87.7,
   "exclude_path": "",
-  "crate_features": ""
+  "crate_features": "backend-stdio"
 }

Diff for: src/block/mod.rs

@@ -4,5 +4,8 @@
 
 /// Contains block request parsing abstraction.
 pub mod request;
-/// Contains block request execution abstraction.
+/// Contains a block request execution abstraction that is based on
+/// [`std::io::Read`](https://doc.rust-lang.org/std/io/trait.Read.html)
+/// and [`std::io::Write`](https://doc.rust-lang.org/std/io/trait.Write.html).
+#[cfg(feature = "backend-stdio")]
 pub mod stdio_executor;