In a stock 7.0 kernel, I do:

make oldconfig
make dep
make bzImage


I get errors that smp_num_cpus is redefined and ultimately undefined in 
ksym.c, amongst others.

Fix is to change include/linux/modules/i386_ksym.ver

#define smp_num_cpus _set_ver(smp_num_cpus)

to

#ifndef smp_num_cpus
#define smp_num_cpus _set_ver(smp_num_cpus)
#endif