Remove obsolete config*.h files

These are ancient and "configunix.h" was being pulled in
via Types.h.  Nothing major, but they were generated for
a 32-bit system and "may" cause problems when used on
64-bit systems.

(That's unlikely though since they haven't all this time.)

include/audacity/Types.h

@@ -823,13 +823,6 @@ using EffectFamilySymbol = ComponentInterfaceSymbol;
       #endif
    #endif //_MSC_VER
 
-   #ifdef __GNUC__
-      #ifndef __CONFIG_UNIX_INCLUDED
-         #define __CONFIG_UNIX_INCLUDED
-         #include "configunix.h"
-      #endif
-   #endif
-
    /* The GCC-elf implementation */
    #ifdef HAVE_VISIBILITY // this is provided by the configure script, is only
    // enabled for suitable GCC versions