RFR: 8355481: Clean up MHN_copyOutBootstrapArguments

[Johan Sjölen]

Hi,

I'd like to integrate this simplification of the code for this loop.

We used to have:

```c++
if (start < 0) {
  for (int pseudo_index = -4; pseudo_index < 0; pseudo_index++) {
    if (start == pseudo_index) {
      if (start >= end || 0 > pos || pos >= buf->length())  break;
      // ...
    }
    start++;
  }
}


That's exactly the same as:


int min_end = MIN2(0, end);
while (-4 <= start && start < min_end) {
  if (pos >= buf->length()) break;
  // ...
  start++;
}


but the latter looks like a conventional loop.

I'd consider this a basic cleanup, which is worth doing in the name of maintainability.

I would have liked to change the `-4` to `-1` into actual names, but I've no clue where those come from. It doesn't seem worth it to change them if they just happen to be a kludge relying on internal details, or something like that.

Testing: GHA Tier1

-------------

Commit messages:
 - Separate it
 - Clarify our behavior
 - We can throw earlier in case of a bad call
 - Remove redundant case
 - Simplify the code a little bit

Changes: https://git.openjdk.org/jdk/pull/24825/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24825&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355481
  Stats: 91 lines in 1 file changed: 47 ins; 41 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/24825.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24825/head:pull/24825

PR: https://git.openjdk.org/jdk/pull/24825