Moved PV_LINK-specific code out of dbLink.c into link types

This required a change to the lset::getValue arguments, removing
the pstat and psevr pointers. Links can still return a non-zero
value from getValue and trigger a LINK:INVALID alarm, but for any
other alarm settings they must manipulate the record themselves.

src/std/link/lnkConst.c

@@ -435,7 +435,7 @@ static long lnkConst_getNelements(const struct link *plink, long *nelements)
 }
 
 static long lnkConst_getValue(struct link *plink, short dbrType, void *pbuffer,
-        epicsEnum16 *pstat, epicsEnum16 *psevr, long *pnRequest)
+        long *pnRequest)
 {
     IFDEBUG(10)
         printf("lnkConst_loadScalar(const@%p, %d, %p, ... (%ld))\n",