Bug 578789 - Deadlock situation when adding new JRE

Don't use syncExec() for tasks that can be done asynchronously. The
listener can be called from the thread that holds already a lock.

Change-Id: Ic2029ae0e395a31564c97e6233ce6596086dd7f6
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.debug/+/190854
Tested-by: JDT Bot <[email protected]>
Reviewed-by: Andrey Loskutov <[email protected]>

Author: iloveeclipse

org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/jres/InstalledJREsBlock.java

@@ -153,7 +153,7 @@ void doRefresh() {
 				fVMList.refresh();
 			}
 			else {
-				display.syncExec(new Runnable() {
+				display.asyncExec(new Runnable() {
 					@Override
 					public void run() {
 						fVMList.refresh();