[bug-diffutils] bug#26927: Diffutils 3.5 make fail by GCC 7.1

[lei-tao9999]

Error info
intprops.h:234:36: error: expected ')' before '(' token
    __builtin_add_overflow (a, b, (__typeof__ ((a) + (b)) *) 0)
Correction method
add “\” after define
# define _GL_ADD_OVERFLOW(a, b, min, max) \
   __builtin_add_overflow (a, b, (__typeof__ ((a) + (b)) *) 0)
# define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \
   __builtin_sub_overflow (a, b, (__typeof__ ((a) - (b)) *) 0)
# define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \
   __builtin_mul_overflow (a, b, (__typeof__ ((a) * (b)) *) 0)
#else