Try to fix Wconvertion warnings
More freebsd porting: type conversions/casts
Support openpam module definition
More freebsd Wconversion fixes
Remove includes from otp.h
More freebsd warning fix
Fix CFLAGS for manage_OTP (include aes & sql)
pam_yubisql doesn't need otp.h nor libyubisql.la
Fix automake building system for freebsd

Thanks to Chris Beggy for the report & patches
Set the default slave_exec to the installation location
Fix empty LDFLAG

Thanks to Chris Beggy for pointing it out
Bugfix: add missing header check
Move AUX_DIR to a more standard location
Update and fix autoconf files