Eliminate more unused variables and compiler warnings.

This change also introduces wrappers for condition variable operations
similar to what we have already for mutex operations.

Almost all the remaining warnings are now in the compiler or non-debug
uses of the CHECK_JIT macro.

Change-Id: I9f492f1582a06065e3a52287c7834adddfbefff9
diff --git a/vm/compiler/Compiler.c b/vm/compiler/Compiler.c
index 63f7512..0f60f20 100644
--- a/vm/compiler/Compiler.c
+++ b/vm/compiler/Compiler.c
@@ -40,8 +40,7 @@
     }
     gDvmJit.compilerQueueLength--;
     if (gDvmJit.compilerQueueLength == 0) {
-        int cc = pthread_cond_signal(&gDvmJit.compilerQueueEmpty);
-        assert(cc == 0);
+        dvmSignalCond(&gDvmJit.compilerQueueEmpty);
     }
 
     /* Remember the high water mark of the queue length */