Fix build of comms/gammu for sparc64

The switch to MODCMAKE_LDFLAGS doesn't work as intended. Nothing gets
passed through to the command line.

Switching it just to LDFLAGS fixes the build on sparc64 and doesn't break
build no amd64.

ok?

(cc MAINTAINER)

--Kurt

Index: Makefile
===================================================================
RCS file: /cvs/ports/comms/gammu/Makefile,v
retrieving revision 1.17
diff -u -p -r1.17 Makefile
--- Makefile 28 May 2022 06:19:58 -0000 1.17
+++ Makefile 15 Aug 2022 17:01:46 -0000
@@ -35,7 +35,7 @@ CONFIGURE_ARGS += -DINSTALL_MAN_DIR:STRI
-Wno-dev

CFLAGS += -I${LOCALBASE}/include
-MODCMAKE_LDFLAGS = -L${LOCALBASE}/lib -liconv -lintl
+LDFLAGS = -L${LOCALBASE}/lib -liconv -lintl

FLAVORS += mysql pgsql
FLAVOR ?=