Makefile.am: add tag option for macos build

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
```
3 jobs for master in 12 minutes and 27 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #400824
amd64 docker
asan-ubsan

00:12:27

passed #400822
amd64 docker
coverage

00:03:18

85.2%
passed #400826
amd64 docker
tsan

00:10:14