fix interior return value documentation

Author: cowtoolz

libc/src/sys/ioctl/linux/ioctl.cpp

@@ -24,11 +24,8 @@ LLVM_LIBC_FUNCTION(int, ioctl, (int fd, unsigned long request, ...)) {
       LIBC_NAMESPACE::syscall_impl<int>(SYS_ioctl, fd, request, data_pointer);
   va_end(vargs);
 
-  // From `man ioctl`:
-  // "Usually, on success zero is returned.  A few ioctl() operations
-  // use the return value as an output parameter and return a
-  // nonnegative value on success.  On error, -1 is returned, and errno
-  // is set to indicate the error."
+  // Some ioctls utilize positive return values; on errors, -1 is returned if
+  // errno is set.
   if (ret < 0) {
     libc_errno = -ret;
     return -1;