don't start the RPC directly;
that might fail if CLIENT_STATE::gui_http is busy.
Instead, set a timer field.
- client: structure ACCT_MGR_OP the same as other GUI_HTTP_OP variants
- client: clarify the comments on GUI_HTTP and GUI_HTTP_OP
Note: GUI_HTTP and GUI_HTTP_OP are misnomers; they refer to
any HTTP op other than scheduler requests and file transfers.
Should change the name, maybe to CLIENT_HTTP*
svn path=/trunk/boinc/; revision=24238
David Anderson