If ABC_HAVE_STDINT_H is defined, standard C99 headers will be used
to define all of the platform-dependent types required. arch_flags
will also no longer be required. This new define is optional and
must be manually enabled by setting ARCHFLAGS.

bridge relates: (1) fix netlist reader to read the latest version written by ZZ, (2) replace printf() with Abc_Print() in pdr so that it will not interfer with bridge messages

move namespace logic into a separate file. It is useful for users of ABC that need to use symbols without the entire baggage of including abc_global.h

make sure all of ABC and related libraries are in the same namespace (when compiled with ABC_NAMESPACE) by removing extern "C" from function definitions