The name g is an alias for R10 and R30, respectively. Have Rconv
print the alias, for consistency with the input language.

Change-Id: Ic3f40037884a0c8de5089d8c8a8efbcdc38c0d56
Reviewed-on: https://go-review.googlesource.com/6630Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>