Handle cases where collected cpu load is NaN
There was a case where calling `OperatingSystemMXBean.getSystemCpuLoad()` returned Double.NaN (the agent was ran on a virtual machine).

The data collected was as follows:

```
TAgentStatBatch(agentId:test-agent, startTimestamp:1441085794300, agentStats:[
    TAgentStat(timestamp:1441087205292, cpuLoad:TCpuLoad(systemCpuLoad:0.026276276276276277, jvmCpuLoad:5.983020928131048E-4), gc:TJvmGc(...)), 
    TAgentStat(timestamp:1441087802597, cpuLoad:TCpuLoad(systemCpuLoad:0.13733025877530106, jvmCpuLoad:9.909711377187762E-6), gc:TJvmGc(...)), 
    TAgentStat(timestamp:1441087802597, cpuLoad:TCpuLoad(systemCpuLoad:NaN, jvmCpuLoad:0.14527027027027026), gc:TJvmGc(...)), 
    TAgentStat(timestamp:1441087802597, cpuLoad:TCpuLoad(systemCpuLoad:NaN, jvmCpuLoad:0.1275), gc:TJvmGc(...)), 
    TAgentStat(timestamp:1441087802597, cpuLoad:TCpuLoad(systemCpuLoad:NaNjvmCpuLoad:0.125), gc:TJvmGc(...)), 
    TAgentStat(timestamp:1441087802597, cpuLoad:TCpuLoad(systemCpuLoad:0.0jvmCpuLoad:0.125), gc:TJvmGc(...))
])
```

Need a NaN check - use `Double.isNaN()`.
(equals check does not work on NaNs as `Double.NaN != Double.NaN`)

diff --git a/profiler/src/main/java/com/navercorp/pinpoint/profiler/monitor/codahale/cpu/CpuLoadCollector.java b/profiler/src/main/java/com/navercorp/pinpoint/profiler/monitor/codahale/cpu/CpuLoadCollector.java
index 3b47af433e..547864abe1 100644
--- a/profiler/src/main/java/com/navercorp/pinpoint/profiler/monitor/codahale/cpu/CpuLoadCollector.java
+++ b/profiler/src/main/java/com/navercorp/pinpoint/profiler/monitor/codahale/cpu/CpuLoadCollector.java
@@ -61,6 +61,6 @@ public class CpuLoadCollector {
     }
 
     private boolean notCollected(double cpuLoad) {
-        return cpuLoad < 0;
+        return cpuLoad < 0 || Double.isNaN(cpuLoad);
     }
 }
['profiler/src/main/java/com/navercorp/pinpoint/profiler/monitor/codahale/cpu/CpuLoadCollector.java']