TwinTree.xs : libtwintree.so install
        mkdir -p TwinTree && \
        cp libtwintree.h TwinTree && \
        h2xs -Oxan TwinTree libtwintree.h -ltwintree
# Removed "lib" ----------------------------^

libtwintree.so : libtwintree.o
        gcc -shared -o libtwintree.so libtwintree.o
# Removed "-Wl,-soname,libtwintree.so" and "-lc"