configure.in: check for setjmp type with CCDLFLAGS

* configure.in (RUBY_SETJMP_TYPE): check for setjmp type after
  CCDLFLAGS is appended to CFLAGS, since __builtin_setjmp can be
  affected.  [ruby-core:62469] [Bug #9818]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45885 b2dd03c8-39d4-4d8f-98ff-823fe69b080e