configure.in: use $DTRACE

* configure.in (RUBY_DTRACE_POSTPROCESS): use configured $DTRACE
  instead of dtrace directly.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44258 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: add $CPPFLAGS

* configure.in (RUBY_DTRACE_POSTPROCESS): $CPPFLAGS is also needed
  to compile.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44259 b2dd03c8-39d4-4d8f-98ff-823fe69b080e