gsmopen: AT+CREG erratic behavior does no more give errors or warnings when badly formatted unsolicited signaling

This lets you specify a FS_SOUNDS_DIR in which to look for the sound
tarballs.  This makes it easier to use git clean -fdx without
downloading the sounds every time.

Previously if --enable-core-odbc-support was set but unixodbc-dev was
not available, we would fail during make rather during configure.

Fix lintian reported issue with version number ending with 0. As per: Debian Developer's Reference section 5.11.2

Fix a bash variable default assignment issue when variable is missing. Also remove unneeded verbosity from the tar extraction.