Add target_arch = "aarch64" and doc configs for each function individually

I thought it would/should have worked to put it on the top of the module
then, at least the target_arch one

Author: Byron

crates/core_arch/src/arm_shared/ex.rs

@@ -5,9 +5,11 @@
 // Not supported: v5, v6-M
 // NOTE: there's no dedicated CLREX instruction in v6 (<v6k); to clear the exclusive monitor users
 // have to do a dummy STREX operation
+#[cfg(target_feature = "aarch64")]
 #[cfg(any(
     all(target_feature = "v6k", not(target_feature = "mclass")), // excludes v6-M
     all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
 ))]
 pub unsafe fn __clrex() {
     extern "C" {
@@ -21,9 +23,11 @@ pub unsafe fn __clrex() {
 /// Executes a exclusive LDR instruction for 8 bit value.
 // Supported: v6K, v7-M, v7-A, v7-R
 // Not supported: v5, v6, v6-M
-#[cfg(
+#[cfg(target_feature = "aarch64")]
+#[cfg(any(
     target_feature = "v6k", // includes v7-M but excludes v6-M
-)]
+    doc
+))]
 pub unsafe fn __ldrexb(p: *const u8) -> u8 {
     extern "C" {
         #[link_name = "llvm.arm.ldrex.p0i8"]
@@ -36,9 +40,11 @@ pub unsafe fn __ldrexb(p: *const u8) -> u8 {
 /// Executes a exclusive LDR instruction for 16 bit value.
 // Supported: v6K, v7-M, v7-A, v7-R, v8
 // Not supported: v5, v6, v6-M
-#[cfg(
+#[cfg(target_feature = "aarch64")]
+#[cfg(any(
     target_feature = "v6k", // includes v7-M but excludes v6-M
-)]
+    doc
+))]
 pub unsafe fn __ldrexh(p: *const u16) -> u16 {
     extern "C" {
         #[link_name = "llvm.arm.ldrex.p0i16"]
@@ -51,9 +57,11 @@ pub unsafe fn __ldrexh(p: *const u16) -> u16 {
 /// Executes a exclusive LDR instruction for 32 bit value.
 // Supported: v6, v7-M, v6K, v7-A, v7-R, v8
 // Not supported: v5, v6-M
+#[cfg(target_feature = "aarch64")]
 #[cfg(any(
     all(target_feature = "v6", not(target_feature = "mclass")), // excludes v6-M
     all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
 ))]
 pub unsafe fn __ldrex(p: *const u32) -> u32 {
     extern "C" {
@@ -69,9 +77,11 @@ pub unsafe fn __ldrex(p: *const u32) -> u32 {
 /// Returns `0` if the operation succeeded, or `1` if it failed
 // supported: v6K, v7-M, v7-A, v7-R
 // Not supported: v5, v6, v6-M
-#[cfg(
+#[cfg(target_feature = "aarch64")]
+#[cfg(any(
     target_feature = "v6k", // includes v7-M but excludes v6-M
-)]
+    doc
+))]
 pub unsafe fn __strexb(value: u32, addr: *mut u8) -> u32 {
     extern "C" {
         #[link_name = "llvm.arm.strex.p0i8"]
@@ -86,9 +96,11 @@ pub unsafe fn __strexb(value: u32, addr: *mut u8) -> u32 {
 /// Returns `0` if the operation succeeded, or `1` if it failed
 // Supported: v6K, v7-M, v7-A, v7-R, v8
 // Not supported: v5, v6, v6-M
-#[cfg(
+#[cfg(target_feature = "aarch64")]
+#[cfg(any(
     target_feature = "v6k", // includes v7-M but excludes v6-M
-)]
+    doc
+))]
 pub unsafe fn __strexh(value: u16, addr: *mut u16) -> u32 {
     extern "C" {
         #[link_name = "llvm.arm.strex.p0i16"]
@@ -103,9 +115,11 @@ pub unsafe fn __strexh(value: u16, addr: *mut u16) -> u32 {
 /// Returns `0` if the operation succeeded, or `1` if it failed
 // Supported: v6, v7-M, v6K, v7-A, v7-R, v8
 // Not supported: v5, v6-M
+#[cfg(target_feature = "aarch64")]
 #[cfg(any(
     all(target_feature = "v6", not(target_feature = "mclass")), // excludes v6-M
     all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
 ))]
 pub unsafe fn __strex(value: u32, addr: *mut u32) -> u32 {
     extern "C" {