Commit based on the commit mentioned below from wr-switch-sw repo.
It required to add a header wrs-msg.h to support "pr_error" function.
"pr_error" will be printed as regular error, all other pr_* are ignored.

userspace/libwr: Print error message on multiple shmem locks

Print error message when shmem is locked or unlocked multiple times.
To be precise it will print error only on even locks or unlocks.

Move the increment of sequence before checking the flags to simplify further
if-conditions.
Signed-off-by: Adam Wujek <adam.wujek@cern.ch>