Make --no-default-features work

If you want to use cmdline loader only, you can run build it with
--no-default-features

Signed-off-by: uran0sH <huangwenyuu@outlook.com>

Author: uran0sH

.buildkite/custom-tests.json

@@ -13,6 +13,14 @@
             "platform": [
                 "x86_64"
             ]
+        },
+        {
+            "test_name": "build-no-default-features",
+            "command": "cargo build --release --no-default-features",
+            "platform": [
+                "x86_64",
+                "aarch64"
+            ]
         }
     ]
 }

src/configurator/mod.rs

@@ -16,6 +16,8 @@
 //! - [PvhBootConfigurator](pvh/struct.PvhBootConfigurator.html): PVH boot protocol parameters
 //!   configurator.
 
+#![cfg(any(feature = "elf", feature = "pe", feature = "bzimage"))]
+
 use vm_memory::{Address, ByteValued, GuestAddress, GuestMemory};
 
 use std::fmt;

src/configurator/x86_64/pvh.rs

@@ -12,6 +12,8 @@
 //! Traits and structs for configuring and loading boot parameters on `x86_64` using the PVH boot
 //! protocol.
 
+#![cfg(any(feature = "elf", feature = "bzimage"))]
+
 use vm_memory::{ByteValued, Bytes, GuestMemory};
 
 use crate::configurator::{BootConfigurator, BootParams, Error as BootConfiguratorError, Result};