Replace epicsTimeERROR with specific error status values

Introduced error status values for epicsTime routines.
The epicsTimeERROR identifier no longer exists, so code that uses it will
no longer compile (deliberately). Replace all uses of it with a specific
error status value.

src/std/dev/devGeneralTime.c

@@ -37,7 +37,7 @@ static int getCurrentTime(double * pseconds)
 {
     epicsTimeStamp ts;
 
-    if (epicsTimeERROR != epicsTimeGetCurrent(&ts)) {
+    if (epicsTimeOK == epicsTimeGetCurrent(&ts)) {
         *pseconds = ts.secPastEpoch + ((double)(ts.nsec)) * 1e-9;
         return 0;
     }