Add i486-unknown-linux-gnu compiler target

Author: jiegec

compiler/rustc_target/src/spec/mod.rs

@@ -1545,6 +1545,7 @@ supported_targets! {
     ("x86_64-unknown-linux-gnux32", x86_64_unknown_linux_gnux32),
     ("i686-unknown-linux-gnu", i686_unknown_linux_gnu),
     ("i586-unknown-linux-gnu", i586_unknown_linux_gnu),
+    ("i486-unknown-linux-gnu", i486_unknown_linux_gnu),
     ("loongarch64-unknown-linux-gnu", loongarch64_unknown_linux_gnu),
     ("loongarch64-unknown-linux-musl", loongarch64_unknown_linux_musl),
     ("m68k-unknown-linux-gnu", m68k_unknown_linux_gnu),

compiler/rustc_target/src/spec/targets/i486_unknown_linux_gnu.rs

@@ -0,0 +1,8 @@
+use crate::spec::Target;
+
+pub fn target() -> Target {
+    let mut base = super::i686_unknown_linux_gnu::target();
+    base.cpu = "i486".into();
+    base.llvm_target = "i486-unknown-linux-gnu".into();
+    base
+}