Cleanup catch Exception when making Java7FSFactory

Catching Exception and rethrowing as Error when the Java7 factory was
not available threw an unexpected error to the caller, but then
confused things by still setting the factory to the default Java
5 version.  A second call to FS.detect(Boolean) would succeed.

Do not throw to the caller. Instead always default to the Java5
factory if the Java7 one is not loading.

Change-Id: I6e9edb257b404d213ff08c44560fdb1672a5c80b

org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java

@@ -138,14 +138,14 @@ public abstract class FS {
 				factory = (FSFactory) activatorClass.newInstance();
 			} catch (ClassNotFoundException e) {
 				// Java7 module not found
-				factory = new FS.FSFactory();
 				// Silently ignore failure to find Java7 FS factory
+				factory = new FS.FSFactory();
 			} catch (UnsupportedClassVersionError e) {
-				// Java7 module not accessible
 				factory = new FS.FSFactory();
-			} catch (Exception e) {
+			} catch (InstantiationException e) {
+				factory = new FS.FSFactory();
+			} catch (IllegalAccessException e) {
 				factory = new FS.FSFactory();
-				throw new Error(e);
 			}
 		}
 		return factory.detect(cygwinUsed);