Allow to export private keys.

Using a workaround that validates passphrase for a secret key.

With GnuPG 2.2.23 and GpgME 1.1.15, a secret key can be exported when the right
passphrase is provided. With a bad passphrase, application crashes.

See https://dev.gnupg.org/T5151

Application may validate a passphrase before invoking engine. Until it is
hopefully fixed in upstream and available in mainstream.

nbproject/private/configurations.xml

@@ -13,6 +13,8 @@
         <gdb_interceptlist>
           <gdbinterceptoptions gdb_all="false" gdb_unhandled="true" gdb_unexpected="true"/>
         </gdb_interceptlist>
+        <gdb_signals>
+        </gdb_signals>
         <gdb_options>
           <DebugOptions>
           </DebugOptions>