fill in dependencies for freeciv-client that were dropped by sdl2-mixer update

Hi,

tb@ found on bulk build that freeciv-client misses audio dependencies
for the libraries that were dropped from sdl2-mixer in favor of
other implementation there. The diff below adds those dependencies to
freeciv-client and fixes the build. I have *not* tested or investigated
if there are other options, like if maybe the port doesn't need those
libraries anymore in WANTLIB with the sdl2-mixer update, due to time
constraints at the moment. If this is worth a test/discussion please
check it; the diff below should fix the build for now and could at
least solve build issue temporarily until this can be looked at more
closely.

ok?

Index: Makefile
===================================================================
RCS file: /cvs/ports/games/freeciv/Makefile,v
retrieving revision 1.131
diff -u -p -r1.131 Makefile
--- Makefile 24 Apr 2023 11:40:39 -0000 1.131
+++ Makefile 29 May 2023 03:30:53 -0000
@@ -1,7 +1,7 @@
COMMENT-main= Civilization clone for X11; multiplayer; game server
COMMENT-client= Freeciv client
COMMENT-share= shared data files for Freeciv
-REVISION-client=0
+REVISION-client=1
REVISION-share= 0

VERSION= 3.0.6
@@ -43,6 +43,11 @@ LIB_DEPENDS-main= archivers/xz \
net/curl \
textproc/icu4c
LIB_DEPENDS-client= archivers/xz \
+ audio/flac \
+ audio/libmikmod \
+ audio/libogg \
+ audio/libvorbis \
+ audio/mpg123 \
databases/sqlite3 \
devel/sdl2-mixer \
net/curl \