try to reduce memory usage on aarch64 and i386:
 - reduce memory use by retaining fewer names within compilation artifacts
 - divise (with codegen-units) the unit in smaller parts to manipulate it

Index: src/bootstrap/bin/rustc.rs
--- src/bootstrap/bin/rustc.rs.orig
+++ src/bootstrap/bin/rustc.rs
@@ -114,6 +114,19 @@ fn main() {
         {
             cmd.arg("-Ztls-model=initial-exec");
         }
+
+        if target.unwrap().contains("aarch64-unknown-openbsd")
+            && crate_name == Some("rustc")
+        {
+            cmd.arg("-Z").arg("fewer-names");
+        }
+        if target.unwrap().contains("i686-unknown-openbsd")
+            && crate_name == Some("rustc_middle")
+        {
+            cmd.arg("-Z").arg("fewer-names");
+            cmd.arg("-C").arg("codegen-units=64");
+        }
+            
     } else {
         // FIXME(rust-lang/cargo#5754) we shouldn't be using special env vars
         // here, but rather Cargo should know what flags to pass rustc itself.