Rollup merge of rust-lang#67255 - tuxillo:remove-i686-unknown-dragonfly, r=alexcrichton

Remove i686-unknown-dragonfly target

DragonFly BSD removed support for i386 a while ago. It only supports x86_64 right now.

Author: Centril

src/librustc_target/spec/i686_unknown_dragonfly.rs

@@ -398,7 +398,6 @@ supported_targets! {
     ("powerpc64-unknown-freebsd", powerpc64_unknown_freebsd),
     ("x86_64-unknown-freebsd", x86_64_unknown_freebsd),
 
-    ("i686-unknown-dragonfly", i686_unknown_dragonfly),
     ("x86_64-unknown-dragonfly", x86_64_unknown_dragonfly),
 
     ("aarch64-unknown-openbsd", aarch64_unknown_openbsd),