src/fmt: make sdb_fmt_tobin return the number of items
src/fmt: make sdb_fmt_tobin return the number of items

radare/sdb,alvarofe/sdb,alvarofe/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,alvarofe/sdb,radare/sdb,radare/sdb,radare/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,radare/sdb,alvarofe/sdb,radare/sdb,radare/sdb,alvarofe/sdb,alvarofe/sdb,radare/sdb,radare/sdb,alvarofe/sdb