Configure: do not force -lm for flac, .pc provides it

configure.ac

@@ -588,7 +588,7 @@ AC_CHECK_FUNCS([if_nameindex if_nametoindex])
 VLC_RESTORE_FLAGS
 
 AS_IF([test -n "$SOCKET_LIBS"], [
-  VLC_ADD_LIBS([access_http access_udp access_tcp access_ftp access_rtmp access_output_udp access_output_shout sap stream_out_standard stream_out_rtp stream_out_raop vod_rtsp rtp oldrc netsync gnutls flac ts audioscrobbler lua remoteosd zvbi audiobargraph_a],[${SOCKET_LIBS}])
+  VLC_ADD_LIBS([access_http access_udp access_tcp access_ftp access_rtmp access_output_udp access_output_shout sap stream_out_standard stream_out_rtp stream_out_raop vod_rtsp rtp oldrc netsync gnutls ts audioscrobbler lua remoteosd zvbi audiobargraph_a],[${SOCKET_LIBS}])
 ])
 AC_SUBST(SOCKET_LIBS)
 
@@ -637,7 +637,7 @@ AC_CHECK_FUNC(getopt_long,, [
 AC_SUBST(GNUGETOPT_LIBS)
 
 AC_CHECK_LIB(m,cos,[
-  VLC_ADD_LIBS([adjust wave ripple psychedelic gradient a52tofloat32 dtstofloat32 x264 goom panoramix rotate noise grain scene kate flac lua chorus_flanger freetype avcodec access_avio swscale postproc i420_rgb faad twolame equalizer spatializer param_eq samplerate freetype mpc dmo quicktime qt4 compressor headphone_channel_mixer normvol audiobargraph_a speex opus mono colorthres extract ball access_imem hotkeys mosaic gaussianblur x26410b hqdn3d anaglyph oldrc ncurses],[-lm])
+  VLC_ADD_LIBS([adjust wave ripple psychedelic gradient a52tofloat32 dtstofloat32 x264 goom panoramix rotate noise grain scene kate lua chorus_flanger freetype avcodec access_avio swscale postproc i420_rgb faad twolame equalizer spatializer param_eq samplerate freetype mpc dmo quicktime qt4 compressor headphone_channel_mixer normvol audiobargraph_a speex opus mono colorthres extract ball access_imem hotkeys mosaic gaussianblur x26410b hqdn3d anaglyph oldrc ncurses],[-lm])
   LIBM="-lm"
 ], [
   LIBM=""