Bug#926909: libblis-openmp-dev: blis needs to provide blas shlib dependency files

[Drew Parsons]

Package: libblis-openmp-dev
Version: 0.5.1-11
Severity: normal

blis needs to provide shlib dependency files so that dh_shlibdeps can
determined the package dependencies for libblas.so.3 (probably for
lapack too).

The problem shows up in slepc builds,
https://buildd.debian.org/status/package.php?p=slepc&suite=experimental

On mpich arches (m68k, sh4), libblis2-openmp and libblis-openmp-dev
set themselves up as the default BLAS,
https://buildd.debian.org/status/fetch.php?pkg=slepc&arch=m68k&ver=3.11.0%2Bdfsg1-1exp2&stamp=1555015766&raw=0
https://buildd.debian.org/status/fetch.php?pkg=slepc&arch=sh4&ver=3.11.0%2Bdfsg1-1exp2&stamp=1555014340&raw=0

Build proceeds, then fails in the dh_shlibs step:

   dh_makeshlibs -a
   dh_shlibdeps -a
dpkg-shlibdeps: error: no dependency information found for /usr/lib/m68k-linux-gnu/libblas.so.3 (used by debian/libslepc-complex3.11/usr/lib/m68k-linux-gnu/libslepc_complex.so.3.11.0)
Hint: check if the library actually comes from a package.
dh_shlibdeps: dpkg-shlibdeps -Tdebian/libslepc-complex3.11.substvars debian/libslepc-complex3.11/usr/lib/m68k-linux-gnu/libslepc_complex.so.3.11.0 returned exit code 25
dpkg-shlibdeps: error: no dependency information found for /usr/lib/m68k-linux-gnu/libblas.so.3 (used by debian/libslepc-real3.11/usr/lib/m68k-linux-gnu/libslepc_real.so.3.11.0)
Hint: check if the library actually comes from a package.
dh_shlibdeps: dpkg-shlibdeps -Tdebian/libslepc-real3.11.substvars debian/libslepc-real3.11/usr/lib/m68k-linux-gnu/libslepc_real.so.3.11.0 returned exit code 25
dh_shlibdeps: Aborting due to earlier error