config: Allow passing arbitrary arguments

to container runtimes using a new configuration key under `build.env`.
This gives users the flexibility to work around issues such as #1012
without having to wait for a new release or creating their own forks of
`cross`.

Author: har7an

src/config.rs

@@ -101,6 +101,10 @@ impl Environment {
         get_possible_image(self, "IMAGE", "IMAGE_TOOLCHAIN", get_target, get_target)
     }
 
+    fn extra_args(&self, target: &Target) -> (Option<Vec<String>>, Option<Vec<String>>) {
+        self.get_values_for("EXTRA_ARGS", target, split_to_cloned_by_ws)
+    }
+
     fn dockerfile(&self, target: &Target) -> (Option<String>, Option<String>) {
         self.get_values_for("DOCKERFILE", target, ToOwned::to_owned)
     }
@@ -409,6 +413,10 @@ impl Config {
         )
     }
 
+    pub fn extra_args(&self, target: &Target) -> Result<Option<Vec<String>>> {
+        self.get_from_ref(target, Environment::extra_args, CrossToml::extra_args)
+    }
+
     pub fn env_volumes(&self, target: &Target) -> Result<Option<Vec<String>>> {
         self.get_from_ref(target, Environment::volumes, CrossToml::env_volumes)
     }

src/cross_toml.rs

@@ -15,6 +15,8 @@ use std::str::FromStr;
 pub struct CrossEnvConfig {
     volumes: Option<Vec<String>>,
     passthrough: Option<Vec<String>>,
+    /// Additional arguments to the underlying container engine
+    extra_args: Option<Vec<String>>,
 }
 
 /// Build configuration
@@ -362,6 +364,14 @@ impl CrossToml {
         )
     }
 
+    pub fn extra_args(&self, target: &Target) -> (Option<&[String]>, Option<&[String]>) {
+        self.get_ref(
+            target,
+            |build| build.env.extra_args.as_deref(),
+            |t| t.env.extra_args.as_deref(),
+        )
+    }
+
     /// Returns the default target to build,
     pub fn default_target(&self, target_list: &TargetList) -> Option<Target> {
         self.build