Add filtering for curl debug output.

Add CURLTR debug channel for libcurl API calls,
and use CURLIO only for libcurl debug output.
Note: need to set gDebugCurlTerse to true for
filtering to take effect, then pass 'debug_on'
to the LLHttpClient methods that require debugging.

indra/newview/skins/default/xui/en-us/floater_merchant_outbox.xml

@@ -10,6 +10,7 @@
     name="floater_merchant_outbox"
     save_rect="true"
     save_visibility="false"
+    rect_control="FloaterOutboxRect"
     reuse_instance="true"
     title="Merchant Outbox"
     width="333">