bug#34935: nanopolish is not reproducible

[Maxim Cournoyer]

$ guix build --check --no-grafts nanopolish
[...]
guix build: error: derivation 
`/gnu/store/7hzcmcwlw83f0wsqmz9nnl1ah54kwks4-nanopolish-0.10.2-1.50e8b5c.drv' 
may not be deterministic: output 
`/gnu/store/m7icaq7642zy0gvnqvymcnn8d088a9s0-nanopolish-0.10.2-1.50e8b5c' 
differs

$ diffoscope "$(guix build nanopolish)" 
/gnu/store/m7icaq7642zy0gvnqvymcnn8d088a9s0-nanopolish-0.10.2-1.50e8b5c

--8<---------------cut here---------------start------------->8---
│ │ │ - 0x000000000000001d (RUNPATH)            Library runpath: 
[/gnu/store/h90vnqw0nwd0hhm1l5dgxsdrigddfmq4-glibc-2.28/lib:/gnu/store/4sqps8dczv3g7rwbdibfz6rf5jlk7w90-gcc-5.5.0-lib/lib:/gnu/store/nq4lsyipmfb0q7g26ra45rwwqrh3x8zw-zlib-1.2.11/lib:/gnu/store/36i633snnhx4mgbnmm5rbkgk3qdi32ka-hdf5-1.8.21/lib:/gnu/store/x4xpcpsqmini25gkrc0h945ml9r609v5-htslib-1.9/lib:/gnu/store/4sqps8dczv3g7rwbdibfz6rf5jlk7w90-gcc-5.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/5.5.0/../../..]
│ │ │ + 0x000000000000001d (RUNPATH)            Library runpath: 
[/gnu/store/h90vnqw0nwd0hhm1l5dgxsdrigddfmq4-glibc-2.28/lib:/gnu/store/4sqps8dczv3g7rwbdibfz6rf5jlk7w90-gcc-5.5.0-lib/lib:/gnu/store/nq4lsyipmfb0q7g26ra45rwwqrh3x8zw-zlib-1.2.11/lib:/gnu/store/36i633snnhx4mgbnmm5rbkgk3qdi32ka-hdf5-1.8.21/lib:/gnu/store/d25i834bs8wvg8mh36bplxg61r6b7vz9-htslib-1.9/lib:/gnu/store/4sqps8dczv3g7rwbdibfz6rf5jlk7w90-gcc-5.5.0-lib/lib/gcc/x86_64-unknown-linux-gnu/5.5.0/../../..]
--8<---------------cut here---------------end--------------->8---

The problem seems to lie in htslib.