Don't mark time_t as deprecated on musl in rustc build

Author: Amanieu

src/unix/linux_like/linux/musl/mod.rs

@@ -1,10 +1,13 @@
 pub type pthread_t = *mut ::c_void;
 pub type clock_t = c_long;
-#[deprecated(
-    since = "0.2.80",
-    note = "This type is changed to 64-bit in musl 1.2.0, \
-            we'll follow that change in the future release. \
-            See #1848 for more info."
+#[cfg_attr(
+    not(feature = "rustc-dep-of-std"),
+    deprecated(
+        since = "0.2.80",
+        note = "This type is changed to 64-bit in musl 1.2.0, \
+                we'll follow that change in the future release. \
+                See #1848 for more info."
+    )
 )]
 pub type time_t = c_long;
 pub type suseconds_t = c_long;