Add extra line to prevent syntax error

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37751 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -487,6 +487,7 @@ EOF
         rb_cv_prog_dtrace_g=yes
       else
         # darwin doesn't need `dtrace -G`
+        rb_cv_prog_dtrace_g=no
       fi
     else
         # DTrace is not available while dtrace command exists