[jdk9] RFR: 8153438: Avoid repeated "Please insert a smart card" popup windows

[Ivan Gerasimov]

Hello!

In order to reduce the number of popup dialog windows during accessing 
the smartcard, it is proposed to first do a silent "probe" step.
Only if this probe succeeded, or if it failed due to that SILENT flag, 
we'll try to re-acquire the key normally (i.e. not silently).

Would you please help review this proposal?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8153438
WEBREV: http://cr.openjdk.java.net/~igerasim/8153438/00/webrev/

With kind regards,
Ivan