Make wxLog::EnableLogging() and wxLogNull thread-specific.

Disabling logging in a single thread (even the main one) shouldn't disable
logs from the background threads which should disable their logging themselves
as/if needed.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61423 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/log.h

@@ -744,7 +744,8 @@ public:
     /**
         Globally enable or disable logging.
 
-        Calling this function with @false argument disables all log messages.
+        Calling this function with @false argument disables all log messages
+        for the current thread.
 
         @see wxLogNull, IsEnabled()
 
@@ -845,7 +846,7 @@ public:
     static bool IsEnabled();
 
     /**
-        Returns true if logging at this level is enabled.
+        Returns true if logging at this level is enabled for the current thread.
 
         This function only returns @true if logging is globally enabled and if
         @a level is less than or equal to the maximal log level enabled for the