Windows shell integration: Add SHCNF_FLUSHNOWAIT to SHChangeNotify

(TortoiseSVN have this flag)

Also do not call SHChangeNotify if there was no change
SocketAPI:  do not have a special case for UPDATE_VIEW on windows

This is a relique on the old times when there was no persistant connection
in the windows plugin
ownsql: fix warning with clang

warning: equality comparison with extraneous parentheses [-Wparentheses-equality]