gold: enable new dtags by default.

This is also the default upstream:
  https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=50701cc170a7c10a72e5ec2c7c6ed31057a31d43

Bug: 31270843
diff --git a/binutils-2.25/gold/options.h b/binutils-2.25/gold/options.h
index 0fa26f1..4bfb2de 100644
--- a/binutils-2.25/gold/options.h
+++ b/binutils-2.25/gold/options.h
@@ -967,7 +967,7 @@
 	      N_("Do not page align data, do not make text readonly"),
 	      N_("Page align data, make text readonly"));
 
-  DEFINE_enable(new_dtags, options::EXACTLY_TWO_DASHES, '\0', false,
+  DEFINE_enable(new_dtags, options::EXACTLY_TWO_DASHES, '\0', true,
 		N_("Enable use of DT_RUNPATH"),
 		N_("Disable use of DT_RUNPATH"));