Promote armv7a-none-eabihf to Tier 2

This is the target for 32-bit Cortex-A bare-metal, when using the FPU.

The target is well tested by the Embedded Devices Working Group, and the
soft-float target (armv7a-none-eabi) is already Tier 2.

Author: thejpster

compiler/rustc_target/src/spec/targets/armv7a_none_eabihf.rs

@@ -30,7 +30,7 @@ pub(crate) fn target() -> Target {
         llvm_target: "armv7a-none-eabihf".into(),
         metadata: TargetMetadata {
             description: Some("Bare Armv7-A, hardfloat".into()),
-            tier: Some(3),
+            tier: Some(2),
             host_tools: Some(false),
             std: Some(false),
         },

src/doc/rustc/src/platform-support.md

@@ -165,6 +165,7 @@ target | std | notes
 `armv7-unknown-linux-musleabi` | ✓ | Armv7-A Linux with musl 1.2.3
 `armv7-unknown-linux-musleabihf` | ✓ | Armv7-A Linux with musl 1.2.3, hardfloat
 [`armv7a-none-eabi`](platform-support/armv7a-none-eabi.md) | * | Bare Armv7-A
+[`armv7a-none-eabihf`](platform-support/armv7a-none-eabi.md) | * |  | Bare Armv7-A, hardfloat
 [`armv7r-none-eabi`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R
 [`armv7r-none-eabihf`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R, hardfloat
 `i586-unknown-linux-gnu` | ✓ | 32-bit Linux (kernel 3.2+, glibc 2.17, original Pentium) [^x86_32-floats-x87]
@@ -300,7 +301,6 @@ target | std | host | notes
 [`armv7-wrs-vxworks-eabihf`](platform-support/vxworks.md) | ✓ |  | Armv7-A for VxWorks
 [`armv7a-kmc-solid_asp3-eabi`](platform-support/kmc-solid.md) | ✓ |  | ARM SOLID with TOPPERS/ASP3
 [`armv7a-kmc-solid_asp3-eabihf`](platform-support/kmc-solid.md) | ✓ |  | ARM SOLID with TOPPERS/ASP3, hardfloat
-[`armv7a-none-eabihf`](platform-support/arm-none-eabi.md) | * |  | Bare Armv7-A, hardfloat
 [`armv7a-vex-v5`](platform-support/armv7a-vex-v5.md) | ? |  | Armv7-A Cortex-A9 VEX V5 Brain, VEXos
 [`armv7k-apple-watchos`](platform-support/apple-watchos.md) | ✓ |  | Armv7-A Apple WatchOS
 [`armv7s-apple-ios`](platform-support/apple-ios.md) | ✓ |  | Armv7-A Apple-A6 Apple iOS

src/doc/rustc/src/platform-support/armv7a-none-eabi.md

@@ -1,7 +1,6 @@
 # `armv7a-none-eabi` and `armv7a-none-eabihf`
 
-* **Tier: 2** for `armv7a-none-eabi`
-* **Tier: 3** for `armv7a-none-eabihf`
+* **Tier: 2**
 * **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the Armv7-A architecture family, supporting