make -j race condition on "make install install-htslib"

[jkbonfield]

If we don't do a "make all all-htslib" first and let the install build do the compilation first, then this trips up when using the joint samtools+htslib tarballs.

The samtools Makefile is running two sub-makes in parallel, to do the building and also to do the installing (which in turn is attempting to do the building).

It's another case of the https://github.com/samtools/htslib/pull/969 basically.

It's not a regression and it's also not following the documented build instructions, so something to schedule for 1.11.