Memory leak iterating multiple queries over cram

The following code consumes memory indefinitely. Memory leak is gone once the change is applied.
Steps:
1. build htslib
2. compile test.c with:
gcc -O0  -ggdb -I htslib/install/include test.c -L htslib/install/lib/ -l:libhts.a -lz -lpthread -llzma -lbz2
3. run ./a.out some.cram chr1
4. watch virtual memory going up in top
5. apply patch, rebuild test.c, notice virtual memory does not change

test.c:
```c++

int main(int argc,char** argv)
{
        hts_itr_t *iter=NULL;
        hts_idx_t *idx=NULL;
        samFile *in = NULL;
        bam1_t *b= NULL;
        bam_hdr_t *header = NULL;
        if(argc!=3) return -1;
        in = sam_open(argv[1], "r");

        if(in==NULL) return -1;
        if ((header = sam_hdr_read(in)) == 0) return -1;

        idx = sam_index_load(in,  argv[1]);
        if(idx==NULL) return -1;

        b = bam_init1();
        fputs("reading\n",stdout);
        do
        {
                if (iter) hts_itr_destroy(iter);
                iter = sam_itr_querys(idx, header, argv[2]);
                if(!iter) return -1;
//              fputs("DO STUFF\n",stdout);
        }
        while (sam_itr_next(in, iter, b) >= 0);

        fputs("done reading\n",stdout);

        hts_itr_destroy(iter);
        bam_destroy1(b);
        hts_idx_destroy(idx);
        bam_hdr_destroy(header);
        sam_close(in);
        return 0;
}
```