musl: enable getrandom on all musl platforms

The existing bindings were added in rust-lang#1399 and limited to targets where
rustc used musl version >= 1.1.20 which was not all musl targets at that
time. Since rust-lang/rust#107129 all musl
targets use musl 1.2.3. Hence, move the binding to the module root so it
is available for all musl targets.

(backport <rust-lang#4346>)
(cherry picked from commit 77d3011)

Author: tamird

src/unix/linux_like/linux/musl/b32/arm/mod.rs

@@ -795,7 +795,3 @@ pub const SYS_process_mrelease: c_long = 448;
 pub const SYS_futex_waitv: c_long = 449;
 pub const SYS_set_mempolicy_home_node: c_long = 450;
 pub const SYS_mseal: c_long = 462;
-
-extern "C" {
-    pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
-}

src/unix/linux_like/linux/musl/b32/powerpc.rs

@@ -745,7 +745,3 @@ pub const SYS_process_mrelease: c_long = 448;
 pub const SYS_futex_waitv: c_long = 449;
 pub const SYS_set_mempolicy_home_node: c_long = 450;
 pub const SYS_mseal: c_long = 462;
-
-extern "C" {
-    pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
-}

src/unix/linux_like/linux/musl/b32/x86/mod.rs

@@ -913,7 +913,3 @@ pub const CS: c_int = 13;
 pub const EFL: c_int = 14;
 pub const UESP: c_int = 15;
 pub const SS: c_int = 16;
-
-extern "C" {
-    pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
-}

src/unix/linux_like/linux/musl/b64/mod.rs

@@ -81,10 +81,6 @@ pub const __SIZEOF_PTHREAD_RWLOCK_T: usize = 56;
 pub const __SIZEOF_PTHREAD_MUTEX_T: usize = 40;
 pub const __SIZEOF_PTHREAD_BARRIER_T: usize = 32;
 
-extern "C" {
-    pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
-}
-
 cfg_if! {
     if #[cfg(target_arch = "aarch64")] {
         mod aarch64;

src/unix/linux_like/linux/musl/mod.rs

@@ -971,6 +971,9 @@ extern "C" {
     pub fn dirname(path: *mut c_char) -> *mut c_char;
     pub fn basename(path: *mut c_char) -> *mut c_char;
 
+    // Addded in `musl` 1.1.20
+    pub fn getrandom(buf: *mut c_void, buflen: size_t, flags: c_uint) -> ssize_t;
+
     // Added in `musl` 1.1.24
     pub fn posix_spawn_file_actions_addchdir_np(
         actions: *mut crate::posix_spawn_file_actions_t,