i386 should be pentiumpro (no SSE2, no ...)

Index: compiler/rustc_target/src/spec/targets/i686_unknown_openbsd.rs
--- compiler/rustc_target/src/spec/targets/i686_unknown_openbsd.rs.orig
+++ compiler/rustc_target/src/spec/targets/i686_unknown_openbsd.rs
@@ -2,7 +2,7 @@ use crate::spec::{base, Cc, LinkerFlavor, Lld, StackPr
 
 pub fn target() -> Target {
     let mut base = base::openbsd::opts();
-    base.cpu = "pentium4".into();
+    base.cpu = "pentiumpro".into();
     base.max_atomic_width = Some(64);
     base.add_pre_link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-m32", "-fuse-ld=lld"]);
     base.stack_probes = StackProbeType::Inline;
