bcc: Add ctypes declarations for new functions (#593)
bcc: Add ctypes declarations for new functions (#593)

Add ctypes declarations for `bpf_attach_tracepoint` and
`bpf_detach_tracepoint` in libbcc.py. It works anyway, but now
it's a bit safer.
brendangregg/bcc,mkacik/bcc,shodoco/bcc,shodoco/bcc,romain-intel/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc,mcaleavya/bcc,brendangregg/bcc,shodoco/bcc,romain-intel/bcc,tuxology/bcc,mkacik/bcc,tuxology/bcc,mkacik/bcc,romain-intel/bcc,iovisor/bcc,mkacik/bcc,mcaleavya/bcc,romain-intel/bcc,iovisor/bcc,brendangregg/bcc,mkacik/bcc,tuxology/bcc,tuxology/bcc,mcaleavya/bcc,iovisor/bcc,romain-intel/bcc,shodoco/bcc,iovisor/bcc,shodoco/bcc,mcaleavya/bcc,iovisor/bcc,mcaleavya/bcc