rustc_target: Rename some target options to avoid tautology

`target.target_endian` -> `target.endian`
`target.target_c_int_width` -> `target.c_int_width`
`target.target_os` -> `target.os`
`target.target_env` -> `target.env`
`target.target_vendor` -> `target.vendor`
`target.target_family` -> `target.os_family`
`target.target_mcount` -> `target.mcount`

compiler/rustc_target/src/spec/windows_uwp_gnu_base.rs

@@ -25,7 +25,7 @@ pub fn opts() -> TargetOptions {
     late_link_args.insert(LinkerFlavor::Lld(LldFlavor::Ld), mingw_libs);
 
     TargetOptions {
-        target_vendor: "uwp".to_string(),
+        vendor: "uwp".to_string(),
         executables: false,
         limit_rdylib_exports: false,
         late_link_args,