Problem linking against vorbisenc in cygwin.

gistfile1.txt

$ ./configure
checking for c++ compiler ... OK
checking for compile with PortAudio ... OK
checking for link with PortAudio ... OK
checking for fltk-config ... OK
checking for compile with fltk ... OK
checking for fltk has FL_GTK_UP_BOX ... OK
checking for link with fltk ... OK
checking for compile with libvorbis ... OK
checking for link with libvorbis ... FAILED
checking for compile with libmp3lame (lame) ... OK
checking for link with libmp3lame (lame) ... OK

configure summary

ogg support:      NO
mp3 support:      YES

You may run "make" now

################# The check configure uses:
check_libvorbis() {

    cat << EOF >tmp.c
#include <vorbis/vorbisenc.h>
int main() {

vorbis_info vi;
vorbis_info_init(&vi);

return 0;
}
EOF
    msg_chkfor "compile with libvorbis"
    if ${CXX} -c tmp.c -o /dev/null 2>&3
    then
        echo "OK"
        msg_chkfor "link with libvorbis"
        if ${CXX} tmp.c -o /dev/null -lvorbisenc 2>&3
        then
            echo "OK"
            echo "#_______________________" >&4
                echo "WITH_LIBVORBIS:=1" >&4
                echo "CXXFLAGS_LIBVORBIS:=" >&4
                echo "CXXFLAGS+=$vorbis_header" >&4
                echo "LDFLAGS+=$vorbis_lib" >&4
                [ "$STATIC" -eq 0 ] && echo "LIBS_LIBVORBIS:=-lvorbisenc" >&4
                echo "SRC_LIBVORBIS:=vorbis_encode.cpp" >&4
                echo "" >&4
                OGG=1
            else
                echo "FAILED"
                echo "WITH_LIBVORBIS:=0" >&4
            fi
        else
            echo "FAILED"
            echo "WITH_LIBVORBIS:=0" >&4
        fi
}

############# Runnig gcc on the tmp file as defined above:
$ gcc tmp.c -o tmp.o -lvorbisenc
/tmp/cca5vP2B.o:tmp.c:(.text+0x16): undefined reference to `_vorbis_info_init'
collect2: ld returned 1 exit status

############# Include files exist:
$ cd /usr/include/vorbis/
$ ls
codec.h  vorbisenc.h  vorbisfile.h