std/thread: Use default stack size from menuconfig for NuttX

* Update comments to clarify the usage of zero as an indication for default stack size configuration
* Adjust conditional compilation to reflect the changes in stack size handling for the NuttX platform

This change improves clarity and consistency in stack size configuration across platforms.

Signed-off-by: Huang Qi <[email protected]>

Author: no1wudi

library/std/src/sys/pal/unix/thread.rs

@@ -14,8 +14,8 @@ pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
 pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024;
 #[cfg(target_os = "vxworks")]
 pub const DEFAULT_MIN_STACK_SIZE: usize = 256 * 1024;
-#[cfg(target_os = "espidf")]
-pub const DEFAULT_MIN_STACK_SIZE: usize = 0; // 0 indicates that the stack size configured in the ESP-IDF menuconfig system should be used
+#[cfg(any(target_os = "espidf", target_os = "nuttx"))]
+pub const DEFAULT_MIN_STACK_SIZE: usize = 0; // 0 indicates that the stack size configured in the ESP-IDF/NuttX menuconfig system should be used
 
 #[cfg(target_os = "fuchsia")]
 mod zircon {
@@ -52,10 +52,10 @@ impl Thread {
         let mut attr: mem::MaybeUninit<libc::pthread_attr_t> = mem::MaybeUninit::uninit();
         assert_eq!(libc::pthread_attr_init(attr.as_mut_ptr()), 0);
 
-        #[cfg(target_os = "espidf")]
+        #[cfg(any(target_os = "espidf", target_os = "nuttx"))]
         if stack > 0 {
             // Only set the stack if a non-zero value is passed
-            // 0 is used as an indication that the default stack size configured in the ESP-IDF menuconfig system should be used
+            // 0 is used as an indication that the default stack size configured in the ESP-IDF/NuttX menuconfig system should be used
             assert_eq!(
                 libc::pthread_attr_setstacksize(
                     attr.as_mut_ptr(),
@@ -65,7 +65,7 @@ impl Thread {
             );
         }
 
-        #[cfg(not(target_os = "espidf"))]
+        #[cfg(not(any(target_os = "espidf", target_os = "nuttx")))]
         {
             let stack_size = cmp::max(stack, min_stack_size(attr.as_ptr()));