libc: fix the pthread_sigmask implementation

The old code didn't work because the kernel expects a 64-bit sigset_t
while the one provided by our ABI is only 32-bit. This is originally
due to the fact that the kernel headers themselves define sigset_t
as a 32-bit type when __KERNEL__ is not defined (apparently to cater
to libc5 or some similarly old C library).

We can't modify the size of sigset_t without breaking the NDK ABI,
so instead perform runtime translation during the call.

Change-Id: Ibfdc3cbceaff864af7a05ca193aa050047b4773f
1 file changed