Fix static build, at least for OSX.
check_lib "${gsm_hdr}" gsm_create -lgsm && break;
done || die "ERROR: libgsm not found"; }
enabled libilbc && require libilbc ilbc.h WebRtcIlbcfix_InitDecode -lilbc
-enabled libmodplug && require libmodplug libmodplug/modplug.h ModPlug_Load -lmodplug
+enabled libmodplug && require_pkg_config libmodplug libmodplug/modplug.h ModPlug_Load
enabled libmp3lame && require "libmp3lame >= 3.98.3" lame/lame.h lame_set_VBR_quality -lmp3lame
enabled libnut && require libnut libnut.h nut_demuxer_init -lnut
enabled libopencore_amrnb && require libopencore_amrnb opencore-amrnb/interf_dec.h Decoder_Interface_init -lopencore-amrnb