linux: add missing pthread_attr_setstack

Adds missing pthread_attr_setstack. The getter function
pthread_attr_getstack is already defined.

(backport <#4349>)
(cherry picked from commit 087ede1)

Author: terohuttunen

libc-test/semver/linux.txt

@@ -4032,6 +4032,7 @@ pthread_attr_setguardsize
 pthread_attr_setinheritsched
 pthread_attr_setschedparam
 pthread_attr_setschedpolicy
+pthread_attr_setstack
 pthread_barrier_destroy
 pthread_barrier_init
 pthread_barrier_t

src/unix/linux_like/mod.rs

@@ -1784,6 +1784,11 @@ extern "C" {
         stackaddr: *mut *mut c_void,
         stacksize: *mut size_t,
     ) -> c_int;
+    pub fn pthread_attr_setstack(
+        attr: *mut crate::pthread_attr_t,
+        stackaddr: *mut c_void,
+        stacksize: size_t,
+    ) -> c_int;
     pub fn memalign(align: size_t, size: size_t) -> *mut c_void;
     pub fn setgroups(ngroups: size_t, ptr: *const crate::gid_t) -> c_int;
     pub fn pipe2(fds: *mut c_int, flags: c_int) -> c_int;