One possible fix to Buddy MIN == MAX case

This is one possible way to fix the 0-length arrays discussed (and made into
assertion failures) in the previous commit.  This works because the Buddy's
`MIN_SIZE_BITS` is instantiated at `MIN_CHUNK_BITS`, and so the change here then
ensures that its `MAX_SIZE_BITS` is strictly greater than `MIN_CHUNK_BITS`.

A different, and possibly better, solution would be to drop the LargeBuddyRange
from CentralMetaRange when `max_page_chunk_size_bits` is computed to be equal to
`MIN_CHUNK_BITS`.

src/snmalloc/backend/meta_protected_range.h

@@ -44,7 +44,7 @@ namespace snmalloc
       bits::next_pow2_bits_const(PAL::page_size);
 
     static constexpr size_t max_page_chunk_size_bits =
-      bits::max(page_size_bits, MIN_CHUNK_BITS);
+      bits::max(page_size_bits, MIN_CHUNK_BITS + 1);
 
     // Central source of object-range, does not pass back to GlobalR as
     // that would allow flows from Objects to Meta-data, and thus UAF