src/sd2.c: Fix a psf_binheader_writef usage bug
src/sd2.c: Fix a psf_binheader_writef usage bug

Unfortunately this bug cannot be found by the compiler and the tests
didn't find it either. It was found during work to improve the type
safety of calls to psf_binheader_writef.

libsndfile/libsndfile,evpobr/libsndfile,erikd/libsndfile,erikd/libsndfile,libsndfile/libsndfile,evpobr/libsndfile,libsndfile/libsndfile,evpobr/libsndfile,erikd/libsndfile,evpobr/libsndfile,erikd/libsndfile,erikd/libsndfile,libsndfile/libsndfile,libsndfile/libsndfile,evpobr/libsndfile