iocInit: only teardown from iocBuildIsolated()

iocShutdown() should only stop threads and cleanup
if the IOC was started with iocBuildIsolated().
If iocBuild() is used then only close CA links
as was done previously.

This is needed as some device support calls epicsExit()
(while holding a record lock).  This make it impossible
to run the full iocShutdown without deadlocking
in scan/callback shutdown, or segfaulting
in doFreeRecord() or dbLockCleanupRecords()

src/ioc/misc/iocInit.c

@@ -72,6 +72,9 @@
 static enum {
     iocVirgin, iocBuilding, iocBuilt, iocRunning, iocPaused, iocStopped
 } iocState = iocVirgin;
+static enum {
+    buildRSRV, buildIsolated
+} iocBuildMode;
 
 /* define forward references*/
 static int checkDatabase(dbBase *pdbbase);
@@ -183,6 +186,7 @@ int iocBuild(void)
     rsrv_init();
 
     status = iocBuild_3();
+    if (!status) iocBuildMode = buildRSRV;
     return status;
 }
 
@@ -199,6 +203,7 @@ int iocBuildIsolated(void)
     if (status) return status;
 
     status = iocBuild_3();
+    if (!status) iocBuildMode = buildIsolated;
     return status;
 }
 
@@ -672,13 +677,16 @@ int iocShutdown(void)
 {
     if (iocState == iocVirgin || iocState == iocStopped) return 0;
     iterateRecords(doCloseLinks, NULL);
-    scanShutdown();
-    callbackShutdown();
-    iterateRecords(doFreeRecord, NULL);
-    dbLockCleanupRecords(pdbbase);
-    asShutdown();
-    iocshFree();
+    if (iocBuildMode==buildIsolated) {
+        scanShutdown();
+        callbackShutdown();
+        iterateRecords(doFreeRecord, NULL);
+        dbLockCleanupRecords(pdbbase);
+        asShutdown();
+        iocshFree();
+    }
     iocState = iocStopped;
+    iocBuildMode = buildRSRV;
     return 0;
 }