Move the freeing of Capabilities later in the shutdown sequence

Fixes a bug whereby the Capability has been freed but other
Capabilities are still trying to steal sparks from its pool.

rts/Capability.c

@@ -767,7 +767,6 @@ shutdownCapability (Capability *cap, Task *task, rtsBool safe)
         }
             
 	debugTrace(DEBUG_sched, "capability %d is stopped.", cap->no);
-        freeCapability(cap);
 	RELEASE_LOCK(&cap->lock);
 	break;
     }
@@ -805,14 +804,28 @@ tryGrabCapability (Capability *cap, Task *task)
 
 #endif /* THREADED_RTS */
 
-void
-freeCapability (Capability *cap) {
+static void
+freeCapability (Capability *cap)
+{
     stgFree(cap->mut_lists);
 #if defined(THREADED_RTS) || defined(PARALLEL_HASKELL)
     freeSparkPool(cap->sparks);
 #endif
 }
 
+void
+freeCapabilities (void)
+{
+#if defined(THREADED_RTS)
+    nat i;
+    for (i=0; i < n_capabilities; i++) {
+        freeCapability(&capabilities[i]);
+    }
+#else
+    freeCapability(&MainCapability);
+#endif
+}
+
 /* ---------------------------------------------------------------------------
    Mark everything directly reachable from the Capabilities.  When
    using multiple GC threads, each GC thread marks all Capabilities

rts/Capability.h

@@ -262,8 +262,8 @@ extern void grabCapability (Capability **pCap);
 // cause all capabilities to context switch as soon as possible.
 void setContextSwitches(void);
 
-// Free a capability on exit
-void freeCapability (Capability *cap);
+// Free all capabilities
+void freeCapabilities (void);
 
 // FOr the GC:
 void markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta, 

rts/Schedule.c

@@ -2114,14 +2114,13 @@ exitScheduler(
 	boundTaskExiting(task);
 	stopTaskManager();
     }
-#else
-    freeCapability(&MainCapability);
 #endif
 }
 
 void
 freeScheduler( void )
 {
+    freeCapabilities();
     freeTaskManager();
     if (n_capabilities != 1) {
         stgFree(capabilities);