Fix #28008: Handle unmanaged classes in c_addrOf with wide pointers

When c_addrOf is called on an unmanaged class in a wide pointer context
(e.g., with CHPL_COMM=gasnet or --no-local), the current implementation
incorrectly tries to take the address of the variable itself using
c_pointer_return, which treats it as a wide pointer. However, unmanaged
class variables are stored as narrow pointers even in wide pointer contexts.

This causes:
- Segfaults with CHPL_COMM=gasnet
- Assertion failures with --no-local and assertions enabled

Solution:
Add specialized overloads of c_addrOf and c_addrOfConst for unmanaged
classes that use c_ptrTo/c_ptrToConst instead of c_pointer_return.
This correctly handles the narrow pointer value rather than taking
the address of the variable.

The fix adds:
- c_addrOf overload for isUnmanagedClass(t) returning c_ptr(void)
- c_addrOfConst overload for isUnmanagedClass(t) returning c_ptrConst(void)

Author: ssam18

modules/standard/CTypes.chpl

@@ -1026,6 +1026,16 @@ module CTypes {
     return c_pointer_return(x);
   }
 
+  // Special handling for unmanaged classes to work with wide pointers
+  // In a wide pointer context, unmanaged class variables are stored as
+  // narrow pointers, but c_pointer_return would try to take the address
+  // of the variable itself, treating it incorrectly as a wide pointer.
+  // Use c_ptrTo instead to get the actual pointer value.
+  @chpldoc.nodoc
+  inline proc c_addrOf(const x: ?t): c_ptr(void) where isUnmanagedClass(t) {
+    return c_ptrTo(x);
+  }
+
   // Added as unstable for 2.4, can be merged into stable version once we're
   // confident in it.
   @chpldoc.nodoc
@@ -1044,6 +1054,12 @@ module CTypes {
     return c_pointer_return_const(x);
   }
 
+  // Special handling for unmanaged classes - see corresponding c_addrOf overload
+  @chpldoc.nodoc
+  inline proc c_addrOfConst(const x: ?t): c_ptrConst(void) where isUnmanagedClass(t) {
+    return c_ptrToConst(x);
+  }
+
   // See note on corresponding c_addrOf overload
   @chpldoc.nodoc
   @unstable("using 'c_addrOfConst' with a domain argument is unstable")