LU-15834 lfs: rid of global variable "error_loc"

LU-15834 lfs: rid of global variable "error_loc"

This patch removes global variable "error_loc", and makes error
string local variables, so that the functions using them are
thread safe.

Test-Parameters: trivial testlist=sanity-flr,sanity-pfl
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: Ib93ff122e84c94b8363b69281b5ff3fa6abb4164
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56852
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>