Create the right cache type ([non-]swappable) on copy on write.

When forking a team, copy on write areas (and therefore caches) are
created for all the areas in the parent team, but they were always
created as swappable. If the parent team had some B_FULL_LOCK areas,
which aren't swappable, the wrong type of cache would be created which
lead to them not being mergeable later on (causing a panic).

Comments about a possibly cleaner way to figure out the cache type
would be welcome.

src/system/kernel/vm/vm.cpp

@@ -55,6 +55,7 @@
 
 #include "VMAddressSpaceLocking.h"
 #include "VMAnonymousCache.h"
+#include "VMAnonymousNoSwapCache.h"
 #include "IORequest.h"
 
 
@@ -2300,7 +2301,8 @@ vm_copy_on_write_area(VMCache* lowerCache,
 
 	// create an anonymous cache
 	status_t status = VMCacheFactory::CreateAnonymousCache(upperCache, false, 0,
-		0, true, VM_PRIORITY_USER);
+		0, dynamic_cast<VMAnonymousNoSwapCache*>(lowerCache) == NULL,
+		VM_PRIORITY_USER);
 	if (status != B_OK)
 		return status;