TLS:
o) The mc_tls field used to store the TLS base when doing context gets and
restores was left a pointer and not converted to a 32-bit integer. This
had the bug of not correctly capturing the TLS value desired by the user,
and the extra nastiness of making the structure the wrong size.
o) The mc_tls field was not being saved by sendsig. As a result, the TLS base
would always be set to NULL when restoring from a signal handler.
Thanks to gonzo for helping track down a bunch of other TLS bugs that came out
of tracking these down.
bdf4700515