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
diff --git a/vm/Thread.c b/vm/Thread.c
index 56cafb4..7dde87c 100644
--- a/vm/Thread.c
+++ b/vm/Thread.c
@@ -1465,9 +1465,8 @@
      */
     dvmUnlockThreadList();
 
-    int cc, oldStatus;
-    oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
-    cc = pthread_create(&threadHandle, &threadAttr, interpThreadStart,
+    ThreadStatus oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
+    int cc = pthread_create(&threadHandle, &threadAttr, interpThreadStart,
             newThread);
     oldStatus = dvmChangeStatus(self, oldStatus);
 
@@ -1843,7 +1842,7 @@
      * need to initiate a GC.  We switch to VMWAIT while we pause.
      */
     Thread* self = dvmThreadSelf();
-    int oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
+    ThreadStatus oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
     dvmLockThreadList(self);
     while (createStatus == 0)
         pthread_cond_wait(&gDvm.threadStartCond, &gDvm.threadListLock);