* configure.in: Check __builtin_popcountl, __builtin_bswap32 and
  __builtin_bswap64.

* internal.h (swap32): Use the configure result for the condition to
  use __builtin_bswap32.
  (swap64): Use the configure result for the condition to use
  __builtin_bswap64.

* bignum.c (ones): Use the configure result for the condition to use
  __builtin_popcountl.
  (bary_unpack_internal): Use appropriate types for swap argument.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41963 b2dd03c8-39d4-4d8f-98ff-823fe69b080e