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/solaris_base.rs

@@ -2,12 +2,12 @@ use crate::spec::TargetOptions;
 
 pub fn opts() -> TargetOptions {
     TargetOptions {
-        target_os: "solaris".to_string(),
-        target_vendor: "sun".to_string(),
+        os: "solaris".to_string(),
+        vendor: "sun".to_string(),
         dynamic_linking: true,
         executables: true,
         has_rpath: true,
-        target_family: Some("unix".to_string()),
+        os_family: Some("unix".to_string()),
         is_like_solaris: true,
         limit_rdylib_exports: false, // Linker doesn't support this
         eh_frame_header: false,