typecast abs() to long int to resolve ambiguity in g++ 7.3.0

[lmogil]

I couldn't build without this change. Error message below.

bddata.cpp:192:38: error: call of overloaded 'abs(unsigned int)' is ambiguous
    if (abs(second.PosB - second.PosB1) > distance) {
                                      ^
In file included from /usr/include/c++/7/cstdlib:75:0,
                 from /usr/include/c++/7/bits/stl_algo.h:59,
                 from /usr/include/c++/7/algorithm:62,
                 from bddata.cpp:1:
/usr/include/stdlib.h:837:12: note: candidate: int abs(int)
 extern int abs (int __x) __THROW __attribute__ ((__const__)) __wur;