Poll statistics moved to worker

Each worker now has a separate structure for collecting the
polling statistics that is passed to epoll_waitevents(). When
the stats are asked for, we loop over all separate stats and
combine them. So, instead of having every statistics of each
thread one cacheline apart, each thread has all its statistics
in one lump that, for obvious reasons, are going to be apart.

The primary purpose of this excersize is to remove the hardwired
nature of the statistics collection. For instance, the admin
thread will be doing I/O but that I/O should not be included
in the statistics of the workers.

include/maxscale/poll_core.h

@@ -81,6 +81,39 @@ typedef struct
 
 extern THREAD_DATA *thread_data;
 
+// TODO: Temporarily moved here.
+/**
+ * The number of buckets used to gather statistics about how many
+ * descriptors where processed on each epoll completion.
+ *
+ * An array of wakeup counts is created, with the number of descriptors used
+ * to index that array. Each time a completion occurs the n_fds - 1 value is
+ * used to index this array and increment the count held there.
+ * If n_fds - 1 >= MAXFDS then the count at MAXFDS -1 is incremented.
+ */
+#define MAXNFDS 10
+
+// TODO: Temporarily moved here.
+typedef struct
+{
+    int64_t n_read;         /*< Number of read events   */
+    int64_t n_write;        /*< Number of write events  */
+    int64_t n_error;        /*< Number of error events  */
+    int64_t n_hup;          /*< Number of hangup events */
+    int64_t n_accept;       /*< Number of accept events */
+    int64_t n_polls;        /*< Number of poll cycles   */
+    int64_t n_pollev;       /*< Number of polls returning events */
+    int64_t n_nbpollev;     /*< Number of polls returning events */
+    int64_t n_nothreads;    /*< Number of times no threads are polling */
+    int32_t n_fds[MAXNFDS]; /*< Number of wakeups with particular n_fds value */
+    int64_t evq_length;     /*< Event queue length */
+    int64_t evq_max;        /*< Maximum event queue length */
+    int64_t blockingpolls;  /*< Number of epoll_waits with a timeout specified */
+} POLL_STATS;
+
+// TODO: Temporarily moved here.
+extern POLL_STATS* pollStats;
+
 /**
  * A file descriptor should be added to the poll set of all workers.
  */