deb: allow use parallel building

src/deb/local.rs

@@ -24,6 +24,26 @@ pub fn build(
 
     let ctx = context::current();
 
+    // Parallel building: find local number of cores, and use that
+    let num_cores = ctx
+        .command("nproc")
+        .output()
+        .map(|output| {
+            if output.status.success() {
+                String::from_utf8_lossy(&output.stdout)
+                    .trim()
+                    .parse::<usize>()
+                    .unwrap_or(1)
+            } else {
+                1 // Default to 1 if nproc fails
+            }
+        })
+        .unwrap_or(1); // Default to 1 if we can't execute the command
+    env.insert(
+        "DEB_BUILD_OPTIONS".to_string(),
+        format!("parallel={}", num_cores),
+    );
+
     if cross {
         log::debug!("Setting up environment for local cross build...");
         cross::setup_environment(&mut env, arch)?;