Unimplement Send and Sync for all platform args

Although unnecessary, as `env::Args` and `env::ArgsOs` provide these
negative impls, this makes other platforms consistent with Unix and make
them more locally clear.

Author: thaliaarchi

library/std/src/sys/args/sgx.rs

@@ -37,6 +37,9 @@ pub struct Args {
     iter: slice::Iter<'static, OsString>,
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl fmt::Debug for Args {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         self.iter.as_slice().fmt(f)

library/std/src/sys/args/unsupported.rs

@@ -7,6 +7,9 @@ pub fn args() -> Args {
     Args {}
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl fmt::Debug for Args {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_list().finish()

library/std/src/sys/args/zkvm.rs

@@ -15,6 +15,9 @@ pub fn args() -> Args {
     Args { i_forward: 0, i_back: 0, count }
 }
 
+impl !Send for Args {}
+impl !Sync for Args {}
+
 impl Args {
     /// Use sys_argv to get the arg at the requested index. Does not check that i is less than argc
     /// and will not return if the index is out of bounds.