build: uname is WinOS-compatible; move to 'Tier1' feature

Cargo.toml

@@ -115,6 +115,7 @@ feat_Tier1 = [
     "nproc",
     "sync",
     "touch",
+    "uname",
     "whoami",
 ]
 ## (primary platforms) feature sets
@@ -194,7 +195,6 @@ feat_require_unix = [
     "stty",
     "timeout",
     "tty",
-    "uname",
 ]
 # "feat_require_unix_utmpx" == set of utilities requiring unix utmp/utmpx support
 # * ref: <https://wiki.musl-libc.org/faq.html#Q:-Why-is-the-utmp/wtmp-functionality-only-implemented-as-stubs?>