Details:
- Removed the #include <stdint.h> from blis.h and inserted a cpp macro block
in bli_type_defs.h that #includes <stdint.h> for C++ and C99, and otherwise
manually typedefs the types we need (which, for now, are unconditionally
int64_t and uint64_t).
- Moved basic typedefs to top of bli_type_defs.h, and comment changes.
- Added cpp macro block to bli_macro_defs.h that #defines restrict as
nothing for C++ and non-C99.