proc: Possible panic while reading uninitialised memory

If uninitialized memory is read loadArrayValues could try to call
cacheMemory with a negative size, which could cause a 'makeslice:
len out of range' panic.

Fixes #354 (partial)

proc/mem.go

@@ -35,6 +35,9 @@ func cacheMemory(mem memoryReadWriter, addr uintptr, size int) memoryReadWriter
 	if !cacheEnabled {
 		return mem
 	}
+	if size <= 0 {
+		return mem
+	}
 	if cacheMem, isCache := mem.(*memCache); isCache {
 		if cacheMem.contains(addr, size) {
 			return mem