>>> Why leave the headers?  Isn’t it risky to leave headers that may be
>>> different from the Samtools that we’re actually linking against?
>>
>> The problem is with our Samtools package(s).  They don't install
>> headers.  I'd better update them to install the headers; then I could
>> just delete the complete "samtools" directory.
>
> Yes that would be best, if that’s fine with you.

Attached is a patch to add a build phase to samtools to install the
headers into $out/include/samtools/.

The second patch is just the updated patch for adding preseq.