out_prometheus_remote_write: update cutoff treshold

This treshold was added to stop metrics older than one hour 
being sent to prometheus. It seems that during compilation, atleast on windows, 
this number gets changed to 817405952, which is significantly lower and 
results in all metrics being thrown.

The treshold have been changed to a static value that persists through compilation.

Signed-off-by: gmhomb <gjerthomb@hotmail.com>

include/cmetrics/cmt_encode_prometheus_remote_write.h

@@ -25,7 +25,7 @@
 #include <prometheus_remote_write/remote.pb-c.h>
 
 #define CMT_ENCODE_PROMETHEUS_REMOTE_WRITE_ADD_METADATA           CMT_FALSE
-#define CMT_ENCODE_PROMETHEUS_REMOTE_WRITE_CUTOFF_THRESHOLD       60L*60L*1000000000L
+#define CMT_ENCODE_PROMETHEUS_REMOTE_WRITE_CUTOFF_THRESHOLD       3600000000000L /* One hour in nanoseconds */
 
 #define CMT_ENCODE_PROMETHEUS_REMOTE_WRITE_SUCCESS                0
 #define CMT_ENCODE_PROMETHEUS_REMOTE_WRITE_ALLOCATION_ERROR       1