Minor clean-up of thread status changes.

Eliminate the obsolete self != NULL test when acquiring the heap lock.
This should be redundant now that threads are added to the thread list
before they are able to allocate.

Switch to using a variable of the ThreadStatus type to store thread
status values rather than an ordinary int.

Change-Id: I8d30e69f20d5321a04f6b49322f13b3577d5a3c4
4 files changed