Add wxGetCpuArchitectureName() for finding out CPU architecture

The returned value is OS-dependent and can be something
like: "x86_64", "x86", "arm64".

Closes https://github.com/wxWidgets/wxWidgets/pull/2121

interface/wx/utils.h

@@ -991,6 +991,15 @@ bool wxIsPlatform64Bit();
 */
 bool wxIsPlatformLittleEndian();
 
+/**
+    Returns the CPU architecture name. This can be, for example, "x86_64",
+    "arm64", or "i86pc". The name for the same CPU running on the same
+    hardware can vary across operating systems.
+
+    @since 3.1.5
+*/
+wxString wxGetCpuArchitectureName();
+
 /**
     Returns a structure containing information about the currently running
     Linux distribution.