[sparc64/base-gcc] Fix build of archivers/unarr

archivers/unarr (just imported) doesn't build as-is. It needs
to set COMPILER to base-clang and ports-gcc.

Fixes the build of sparc64.

ok?

(cc maintiner)

--Kurt

Index: Makefile
===================================================================
RCS file: /cvs/ports/archivers/unarr/Makefile,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 Makefile
--- Makefile 26 Jul 2021 04:07:03 -0000 1.1.1.1
+++ Makefile 29 Jul 2021 21:32:19 -0000
@@ -16,6 +16,9 @@ MAINTAINER = Omar Polo <op@omarpolo.com
# LGPLv3
PERMIT_PACKAGE = Yes

+COMPILER = base-clang ports-gcc
+COMPILER_LANGS = c
+
WANTLIB += bz2 lzma z

MASTER_SITES = ${HOMEPAGE:=releases/download/v${V}/}