Makefile.am: add tag option to libtool flag

Otherwise, it fails to build on macos with libtool's complain.

libtool: compile: unable to infer tagged configuration
libtool:   error: specify a tag with '--tag'
make[2]: *** [src/filesystem/darwin/libmedialibrary_macos_la-DeviceLister.lo] Error 1
make[1]: *** [all] Error 2