Fill in missing target metadata

Author: qb42

compiler/rustc_target/src/spec/targets/i586_unknown_redox.rs

@@ -11,7 +11,12 @@ pub(crate) fn target() -> Target {
 
     Target {
         llvm_target: "i586-unknown-redox".into(),
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata {
+            description: Some("32-bit x86 Redox OS (PentiumPro)".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
         pointer_width: 32,
         data_layout:
             "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128"

compiler/rustc_target/src/spec/targets/x86_64_unknown_linux_none.rs

@@ -14,9 +14,9 @@ pub(crate) fn target() -> Target {
     Target {
         llvm_target: "x86_64-unknown-linux-none".into(),
         metadata: TargetMetadata {
-            description: None,
-            tier: None,
-            host_tools: None,
+            description: Some("64-bit Linux with no libc".into()),
+            tier: Some(3),
+            host_tools: Some(false),
             std: Some(false),
         },
         pointer_width: 64,

compiler/rustc_target/src/spec/targets/xtensa_esp32_espidf.rs

@@ -9,7 +9,12 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata {
+            description: Some("Xtensa ESP32".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
 
         options: TargetOptions {
             endian: Endian::Little,

compiler/rustc_target/src/spec/targets/xtensa_esp32s2_espidf.rs

@@ -9,7 +9,12 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata {
+            description: Some("Xtensa ESP32-S2".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
 
         options: TargetOptions {
             endian: Endian::Little,

compiler/rustc_target/src/spec/targets/xtensa_esp32s3_espidf.rs

@@ -9,7 +9,12 @@ pub(crate) fn target() -> Target {
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-v1:8:8-i64:64-i128:128-n32".into(),
         arch: Arch::Xtensa,
-        metadata: TargetMetadata { description: None, tier: None, host_tools: None, std: None },
+        metadata: TargetMetadata {
+            description: Some("Xtensa ESP32-S3".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
 
         options: TargetOptions {
             endian: Endian::Little,