test_syntax.rb: fix test error

* test/ruby/test_syntax.rb (test_syntax): escape interpolation to use
  the value passed by ARGV.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39955 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
internal.h: use SIGNEDNESS_OF_TIME_T

* configure.in (RUBY_REPLACE_TYPE): define SIGNEDNESS_OF_type same as
  check_signedness of mkmf.rb.
* internal.h (TIMET_MAX, TIMET_MIN, TIMET_MAX_PLUS_ONE): use
  SIGNEDNESS_OF_TIME_T.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39956 b2dd03c8-39d4-4d8f-98ff-823fe69b080e