• bignum.c (bary_mul): Use simple multiplication if yl is small.
  (rb_cstr_to_inum): Invoke bigsq instead of bigmul0.
  (bigsq): Re-implemented.
  (bigmul0): Invoke bigsq if two arguments are identical.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e