 * minor changes to bgzf: return NULL if fd == -1  * suggested by {kdj,jm18}@sanger.ac.uk
 * minor changes to bgzf: return NULL if fd == -1
 * suggested by {kdj,jm18}@sanger.ac.uk


git-svn-id: ba63ac760bf0f03e6bf5520b5300f1a364b8a096@306 fd675618-d7d1-4fc3-a54f-e58cce934862

pjotrp/samtools,pjotrp/samtools,pjotrp/samtools