Give lang/guile2 DPB_PROPERTIES=parallel?

I'm noticing lang/guile2 being one of the longer builds that doesn't
do multiple jobs at once for the sparc64 builds. I've run it with
MAKE_JOBS=4 several times on my amd64 test box and had no issues.

ok to add the following to lang/guile2?

--Kurt

Index: Makefile
===================================================================
RCS file: /cvs/ports/lang/guile2/Makefile,v
retrieving revision 1.23
diff -u -p -r1.23 Makefile
--- Makefile 16 Jul 2019 21:29:41 -0000 1.23
+++ Makefile 2 Dec 2019 19:46:42 -0000
@@ -5,6 +5,8 @@

BROKEN-powerpc= Segmentation fault (core dumped)

+DPB_PROPERTIES= parallel
+
COMMENT= GNU's Ubiquitous Intelligent Language for Extension
# '