3.100 will not build mp3x if --enable-dynamic-frontends is used. Looks like maybe a .o file is missing.
Using GCC on linux.
./configure --prefix=/usr --libdir=/usr/lib64 --enable-mp3x --enable-mp3rtp --enable-nasm --enable-dynamic-frontends
libtool: link: gcc -I/usr/include/gtk-1.2 -I/usr/include/glib-1.2 -I/usr/lib64/glib/include -o .libs/mp3x mp3x.o gtkanal.o gpkplotting.o main.o brhist.o console.o get_audio.o lametime.o parse.o timestatus.o -rdynamic ../libmp3lame/.libs/libmp3lame.so -lncurses -L/usr/lib64 /usr/lib64/libgtk.so /usr/lib64/libgdk.so /usr/lib64/libgmodule.so /usr/lib64/libglib.so /usr/lib64/libXext.so /usr/lib64/libX11.so /usr/lib64/libxcb.so /usr/lib64/libXau.so /usr/lib64/libXdmcp.so -ldl -lm
/usr/bin/ld: gtkanal.o: in function gtkmakeframe':
gtkanal.c:(.text+0xcb): undefined reference tohip_set_pinfo'
/usr/bin/ld: gtkanal.c:(.text+0xf7): undefined reference to hip_set_pinfo'
/usr/bin/ld: gtkanal.c:(.text+0x298): undefined reference tohip_set_pinfo'
collect2: error: ld returned 1 exit status
Makefile:476: recipe for target 'mp3x' failed
make[2]: *** [mp3x] Error 1
Also seen in comment 3 on this page:
https://bugzilla.redhat.com/show_bug.cgi?id=1505107