std.posix: include PermissionDenied to handle errno 13

This is to handle the issue described in ziglang#22442.

There is an AccessDenied already there, but posix describes errno 13
specifically as "Permission Denied".

lib/std/posix.zig

@@ -1168,6 +1168,7 @@ pub const WriteError = error{
     NoSpaceLeft,
     DeviceBusy,
     InvalidArgument,
+    PermissionDenied,
 
     /// In WASI, this error may occur when the file descriptor does
     /// not hold the required rights to write to it.
@@ -1274,6 +1275,7 @@ pub fn write(fd: fd_t, bytes: []const u8) WriteError!usize {
             .CONNRESET => return error.ConnectionResetByPeer,
             .BUSY => return error.DeviceBusy,
             .NXIO => return error.NoDevice,
+            .ACCES => return error.PermissionDenied,
             else => |err| return unexpectedErrno(err),
         }
     }