util-linux: link scriptreplay with libm (for isnan)

- Cherry-pick a patch from upstream to link scriptreplay to libm (for
  "isnam").
- Add a patch that improves the detection of isnan when using uClibc.
  This patch is for util-linux v2.29.1 and must be adapted to their
  master branch to be submitted upstream.

Fixes:
  http://autobuild.buildroot.net/results/2c2/2c29a78ed81ca844a87dcd076ab3e14ea080296d
  http://autobuild.buildroot.net/results/404/404b10f359b2ae8a7216729fa1bab37fed2d3d4c



Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>