Start over on android support
Add cpu_set_t definition for Android

This is defined in Bionic, but the Android NDK has the definitions
stripped out.  This definition works for up to 32 independent CPUs,
which is the maximum supported by the kernel at the moment as well.

Taken from:
   https://android.googlesource.com/platform/bionic.git/+/master/libc/include/sched.h