#7 C++ compatibility

[Tony Yat-Tung Cheung]

Hi,

I am linking MRTd with C++ codes.

The only problem is that "explicit" is now a keyword of C++, but it is not a keyword in C.

I have to renamed explicit to _explicit (or something else) in config/bgpconf.c and include/view.h.

I hope it would be fixed, so it's easier to link with C++ codes. Thanks!

Tony Cheung