Define wxSOCKET_XXX flags as wxSOCKET_XXX_READ|wxSOCKET_XXX_WRITE.

Define wxSOCKET_XXX flags as wxSOCKET_XXX_READ|wxSOCKET_XXX_WRITE.

The recently introduced (in r72591) wxSOCKET_{WAITALL,NOWAIT}_{READ,WRITE}
flags weere for some reason completely different and unrelated to the existing
bidirectional wxSOCKET_{WAITALL,NOWAIT} ones. Change this by defining the
bidirectional version simply as the sum of the two others. This makes much
more sense than testing for either wxSOCKET_XXX or wxSOCKET_XXX_READ or
wxSOCKET_XXX_WRITE being specified.

And it also fixes an assert in wxSocketWaitModeChanger where a sanity check
failed when this class was used with wxSOCKET_WAITALL|wxSOCKET_WAITALL_READ.

See #14506.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72828 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775