Rollup merge of #138949 - madsmtm:rename-to-darwin, r=WaffleLapkin

Rename `is_like_osx` to `is_like_darwin`

Replace `is_like_osx` with `is_like_darwin`, which more closely describes reality (OS X is the pre-2016 name for macOS, and is by now quite outdated; Darwin is the overall name for the OS underlying Apple's macOS, iOS, etc.).

``@rustbot`` label O-apple
r? compiler

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -352,7 +352,7 @@ pub struct CodegenContext<B: WriteBackendMethods> {
     pub is_pe_coff: bool,
     pub target_can_use_split_dwarf: bool,
     pub target_arch: String,
-    pub target_is_like_osx: bool,
+    pub target_is_like_darwin: bool,
     pub target_is_like_aix: bool,
     pub split_debuginfo: rustc_target::spec::SplitDebuginfo,
     pub split_dwarf_kind: rustc_session::config::SplitDwarfKind,
@@ -1216,7 +1216,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         is_pe_coff: tcx.sess.target.is_like_windows,
         target_can_use_split_dwarf: tcx.sess.target_can_use_split_dwarf(),
         target_arch: tcx.sess.target.arch.to_string(),
-        target_is_like_osx: tcx.sess.target.is_like_osx,
+        target_is_like_darwin: tcx.sess.target.is_like_darwin,
         target_is_like_aix: tcx.sess.target.is_like_aix,
         split_debuginfo: tcx.sess.split_debuginfo(),
         split_dwarf_kind: tcx.sess.opts.unstable_opts.split_dwarf_kind,