Anecdotal evidence suggests that a single EnumPrinters() call

Anecdotal evidence suggests that a single EnumPrinters() call
specifying both PRINTER_ENUM_LOCAL and PRINTER_ENUM_CONNECTIONS
catches more printers in some circumstances than two EnumPrinters()
calls each specifying just one of them. We'll try it for a bit; if
it goes wrong I might have to put back the two original calls as
well and sort out some means of removing duplicate printers from the
list.

git-svn-id: svn://svn.tartarus.org/sgt/putty@1829 cda61777-01e9-0310-a592-d414129be87e