with latest gcc, abook doesn't compile. The symptoms and solution are described in detail in posts:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=777764
https://gcc.gnu.org/gcc-5/porting_to.html
the solution is:
CFLAGS = -std=gnu89
Please update this to the sourcec (I'm not sure where in the .am .in files)
thank you for reporting
std=gnu89
is a workaround.I also opted for (another) workaround:
-fgnu89-inline
since I was unable to get it extern inline "the-right-way" while staying warning-free with >= C99.fixed (back in 54f8e4ac4e0bdf7622909c4cdf5768bebe72460c)