package/gensio: bump to version 1.5.1

- Update indentation of hash file (2 spaces)
- This will fix a build failure without threads thanks to
  https://github.com/cminyard/gensio/commit/8918de5b30f90b826c48064e9ee92304b63ffe85
  and associated upstream patch

Fixes:
 - http://autobuild.buildroot.org/results/e94d0e0b46afc1223a74bcc471909f4adef0d6f3



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>