google-authenticator-libpam does not contain Makefile

[Chaz6]

$ git submodule update --init --recursive && cd src && ./build.sh

Building without internal key
rm -rf bin
rm -f *.o config.h *.gcno *.gcda *.gcov coverage*.html
(cd google-authenticator-libpam && make clean)
make[1]: Entering directory '/home/chaz/git/github.com_arcanericky_ga-cmd/src/google-authenticator-libpam'
make[1]: *** No rule to make target 'clean'.  Stop.
make[1]: Leaving directory '/home/chaz/git/github.com_arcanericky_ga-cmd/src/google-authenticator-libpam'
make: *** [makefile:56: clean] Error 2

$ ls google-authenticator-libpam/
bootstrap.sh  build  configure.ac  contrib  CONTRIBUTING.md  examples  FILEFORMAT  LICENSE  Makefile.am  man  README.md  src  tests  totp.html  utc-time