deb: allow use parallel building

src/context/unshare.rs

@@ -208,7 +208,7 @@ impl UnshareDriver {
         }
 
         cmd.arg("--").arg("bash").arg("-c").arg(format!(
-            "mount -t proc proc /proc; mount -t devpts devpts /dev/pts; mount --bind /dev/pts/ptmx /dev/ptmx; {} {}",
+            "mount -t proc proc /proc; mkdir /dev/pts; mount -t devpts devpts /dev/pts; touch /dev/ptmx; mount --bind /dev/pts/ptmx /dev/ptmx; {} {}",
             program,
             args.join(" ")
         ));

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)?;

src/deb/mod.rs

@@ -277,6 +277,11 @@ mod tests {
     /// The GCC package is complex and hard to build, with specific stages
     /// and system-bound scripts. Building it requires specific things that
     /// we want to ensure are not broken.
+    /// NOTE: Ideally, we want to run this in CI, but it takes more than 20h
+    /// to fully build the gcc-15 package on an amd64 builder, which is too
+    /// much time.
+    #[ignore]
+    #[cfg(target_arch = "x86_64")]
     #[tokio::test]
     #[test_log::test]
     #[serial]