Fix a integer trauction issue - calculating the current time in

nanoseconds in 32-bit expression would cause pthread_cond_timedwait
to time out immediately.  Add explicit casts to the TimeValue::TimeValue
ctor that takes a struct timeval and change the NanoSecsPerSec etc
constants defined in TimeValue to be uint64_t so any other calculations
involving these should be promoted to 64-bit even when lldb is built
for 32-bit.

<rdar://problem/11204073>, <rdar://problem/11179821>, <rdar://problem/11194705>.

llvm-svn: 154250