Refs #214, #221, #246. Fixed the getrf overflow bug on Windows.

I used a smaller threshold since the stack size is 1MB on windows.

driver/level3/level3_thread.c

@@ -50,7 +50,7 @@
 
 //The array of job_t may overflow the stack.
 //Instead, use malloc to alloc job_t. 
-#if MAX_CPU_NUMBER > 210
+#if MAX_CPU_NUMBER > BLAS3_MEM_ALLOC_THRESHOLD
 #define USE_ALLOC_HEAP
 #endif