[Common] Add synchronization to privilege checking

[Common] Add synchronization to privilege checking

common::tools::CheckAccess() can be called from multiple threads in the
same time. (This happens in web service apps, which now are running as
separate threads of a single process.)
This commit adds synchronization of the access of this function's static
resources.

[Verification] Code compiles. The code works fine in a single-threaded
app

Change-Id: I4af0715d3605284bf82b2abe207dabe024986d25
Signed-off-by: Pawel Wasowski <p.wasowski2@samsung.com>