Use C-locale for numeric/string conversion routines

(strtod, ...) or config file parsing might fail.

Cherry picked from commit 5b8de971a4b81bc2bd6de0ffc6386587226295c6:
> Change-Id: I649f29bbf87222399a0c2d1ed5a3bf136c613b9b
> BUG: 1117951
> Signed-off-by: Anders Blomdell <anders.blomdell@control.lth.se>
> Reviewed-on: http://review.gluster.org/8299
> Tested-by: Gluster Build System <jenkins@build.gluster.com>
> Reviewed-by: Prashanth Pai <ppai@redhat.com>
> Reviewed-by: Vijay Bellur <vbellur@redhat.com>

Change-Id: I649f29bbf87222399a0c2d1ed5a3bf136c613b9b
BUG: 1157107
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/9132
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>