[parrot/parrot] 84807d: fix clang optimizer increment issue GH #774

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/parrot/parrot
  Commit: 84807d1b7442924ab46ad783bbbc6c08549d8187
      https://github.com/parrot/parrot/commit/84807d1b7442924ab46ad783bbbc6c08549d8187
  Author: Reini Urban <rurban at cpanel.net>
  Date:   2014-03-07 (Fri, 07 Mar 2014)

  Changed paths:
    M src/pmc/integer.pmc
    M t/pmc/bigint.t

  Log Message:
  -----------
  fix clang optimizer increment issue GH #774

have to use volatile scratch registers in Parrot_Integer_increment_orig to avoid
skipping overflow sementics: -1 => MAXINT
fixes t/pmc/bigint.t test negate_min_integer