audio/libmysofa: specify c lang

This is c language only port. Specifying this fixes lib-depends-check
on sparc64 showing Extra: estdc++.19

okay?
Index: Makefile
===================================================================
RCS file: /cvs/ports/audio/libmysofa/Makefile,v
retrieving revision 1.3
diff -u -p -u -r1.3 Makefile
--- Makefile 11 Mar 2022 18:20:15 -0000 1.3
+++ Makefile 21 Dec 2024 18:59:17 -0000
@@ -6,6 +6,8 @@ GH_ACCOUNT= hoene
GH_PROJECT= libmysofa
GH_TAGNAME= v${VER}

+REVISION= 0
+
SHARED_LIBS= mysofa 0.0

HOMEPAGE= https://github.com/hoene/libmysofa
@@ -18,6 +20,7 @@ PERMIT_PACKAGE= Yes
WANTLIB= m z

COMPILER= base-clang ports-clang ports-gcc
+COMPILER_LANGS= c

MODULES= devel/cmake