Prior to the introduction of HTSlib, SAMtools and BCFtools were distributed
in a single samtools-0.1.x package.
This old version remains available from SBo as samtools-legacy

Samtools is now distributed as an individual package.
Installation is set up so that the code uses an external HTSlib (also at SBo).
Although deprecated upstream, in the case that people need parts of samtools-legacy
(e.g header files or libbam) these can be installed from this package by modifying
the samtools.Slackbuild.

Note that the sam.h of htslib differs from sam.h coming with samtools.