Suppress unsafe warnings of MSVC

Added a define to suppress MSVC warning “C4996:
This function or variable may be unsafe.”
If the code is really "unsafe" then it is unsafe on
other platforms as well; so fixing these warnings just
for MSVC builds, would clutter the code and wouldn't help
in fixing issues that might exist on other platforms.
Using the same functions across all supported platforms
keeps the code clean and helps in writing code that is
safe across all platforms.

Change-Id: I470072eda4f8174bb911567ef3f061a3582ba449
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>