Fix incorrect offset into fastq header in name2 mode

The offset to skip over the first name in the fastq header
was being applied twice, potentially causing the search for
the comment part to fall off the end of the allocated string.

Thanks to John Marshall for reporting this.

sam.c

@@ -3735,7 +3735,7 @@ static int fastq_parse1(htsFile *fp, bam1_t *b) {
     }
 
     l = x->name.l;
-    char *s = x->name.s + i;
+    char *s = x->name.s;
     while (i < l && !isspace_c(s[i]))
         i++;
     if (i < l) {