libsndfile: Fix satisfy_deb line.

libsndfile-dev is a virtual package ("apt-get install libsndfile-dev" will
actually install libsndfile1-dev). The current code cannot properly
handle/detect it as being available ("apt-cache show" output is different
from what it expects), hence it'll try to build from source instead.

Fix this by adding libsndfile1-dev as alternative.
Merge pull request #107 from uwehermann/libsndfile_fix

libsndfile: Fix satisfy_deb line.