Simplified several Ruby bigint operations by removing redundant mpz_init calls:
- mrb_bint_add_n: mpz_add now handles initialization internally
- mrb_bint_sub_n: mpz_sub now handles initialization internally
- mrb_bint_add_ii: mpz_add now handles initialization internally
- mrb_bint_sub_ii: mpz_sub now handles initialization internally
These changes demonstrate the benefit of the *_auto API - operations that
previously required separate init + operation calls now work with just
the operation call, as the simplified functions handle memory allocation
automatically.
Co-authored-by: Claude <noreply@anthropic.com>
Yukihiro "Matz" Matsumoto
e9c896408a