Add wxPlatformInfo::GetCpuArchitectureName()

This provides the same information as wxGetCpuArchitectureName(), but is
consistent with the other wxPlatformInfo accessors, which also
correspond to the existing wxGetXXX() functions, and makes it more
convenient to use this information in the application code as now
everything is available via wxPlatformInfo instead of having to use
different functions for different pieces.

interface/wx/platinfo.h

@@ -368,6 +368,15 @@ public:
     */
     wxEndianness GetEndianness() const;
 
+    /**
+        Returns the CPU architecture name, if available.
+
+        @see wxGetCpuArchitectureName()
+
+        @since 3.1.5
+     */
+    wxString GetCpuArchitectureName() const;
+
     /**
         Returns the run-time major version of the OS associated with this
         wxPlatformInfo instance.