[core] do not assert when casting huge enum uint64_t into int64_t

[ferdymercury]

This Pull request:

Changes or fixes:

even if it becomes negative due to the overflow.

Fixes #17697

Tested that the Python reproducer in #17697 no longer crashes

code = """
struct Foo
{
  enum E {
    BIG = ((unsigned long long)1)<<63
  };
};
"""

import ROOT
ROOT.gInterpreter.Declare (code)

f = ROOT.Foo()
f.BIG
(Foo::E::Foo::E::BIG) : (internal_enum_type_t) -9223372036854775808

Checklist:

• tested changes locally
• updated the docs (if necessary)

[pcanal]

I suppose this is an okay solution. It would be even better if we could return the correct value (would likely require more significant changes)

[dpiparo]

Do we maybe need a unit test for this?

[github-actions]

Test Results

    22 files      22 suites   3d 12h 4m 54s ⏱️
 3 811 tests  3 811 ✅ 0 💤 0 ❌
76 733 runs  76 733 ✅ 0 💤 0 ❌

Results for commit dffde5d.