Don't use multi-sampling in wxGLAttributes::Defaults()

This prevents wxGLCanvas from working on limited OpenGL implementations
not providing it, such as VMWare OpenGL driver, and doesn't seem to be
really necessary as multi-sampling can always be explicitly requested if
the application does want to use it.

Closes #23121.

docs/changes.txt

@@ -27,6 +27,10 @@ Changes in behaviour not resulting in compilation errors
 - wxMSW doesn't support versions of Microsoft Windows before Windows 7. If you
   need Windows XP or Vista support, please use wxWidgets 3.2.
 
+- wxGLCanvas doesn't use multi-sampling by default any longer, please use
+  wxGLAttributes::Samplers(1).SampleBuffers(4) explicitly if you need to keep
+  using the same attributes that were previously used by default.
+
 - As first mentioned in 3.0 release notes, the value of wxTHREAD_WAIT_DEFAULT,
   used by wxThread::Delete() and Wait() by default, has changed from
   wxTHREAD_WAIT_YIELD to wxTHREAD_WAIT_BLOCK for safety and consistency.

include/wx/glcanvas.h

@@ -165,7 +165,7 @@ public:
     // instead of in port-specific files.
     wxGLAttributes& Defaults()
     {
-        return RGBA().Depth(16).DoubleBuffer().SampleBuffers(1).Samplers(4);
+        return RGBA().Depth(16).DoubleBuffer();
     }
 };