#55 Empty library leads to libtool error -> warning needed

[Joerg Faschingbauer]

h = [
]

cpp = [
]

LIBRARY(members=[H(filename=f) for f in h] + [CXX(filename=f) for f in cpp])

leads to an empty library. while this doesn't seem to be a problem with non-libtool builds, automake/libtool complains like follows,

make[1]: Entering directory `/home/jfasch/atronic/build/comm_lib-1.0.0/os/os_linux'
make[1]: *** No rule to make target `libcomm_lib_os_os_linux.lo', needed by `libcomm_lib_os_os_linux.la'. Stop.

(no idea why a .lo is generated with the same basename as the .la)