BaseTools: Improve the file saving and copying reliability

BaseTools: Improve the file saving and copying reliability

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2079

The Basetool CopyFileOnChange() and SaveFileOnChange()
functions might raise the IOError occasionally when build
in Windows with multi-process and build cache enabled.
The CopyFileOnChange() and SaveFileOnChange() might be invoked
in multiple sub-processes simultaneously, and this patch adds
global locks to sync these functions invoking which can
harden their reliability.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Signed-off-by: Steven Shi <steven.shi@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>