Expose the ILP32/LP64 programming environments based on

__ILP32__/__LP64__ instead of by architecture.

The list was incomplete (previous commits purged invalid architectures,
like __alpha__, but failed to add new ones). It's best to base the symbol
presence on whether or not the architecture is ILP32 / LP64 capable, per
the compiler.

This fixes the ILP32/LP64 program environments on some architectures like
arm64, and by proxy fixes the tests on those architectures.

MFC after:	1 month
Reviewed by:	no one (timed out on feedback from imp)
Differential Revision:	D10787

usr.bin/getconf/progenv.gperf

@@ -30,11 +30,11 @@ static const struct map *in_word_set(const char *str);
  * be updated.  (We cheat here and define the supported environments
  * statically.)
  */
-#if defined(__sparc64__) || defined(__amd64__)
+#ifdef	__LP64__
 #define	have_LP64_OFF64		NULL
 #endif
 
-#if defined(__i386__) || defined(__powerpc__)
+#ifdef	__ILP32__
 #define	have_ILP32_OFFBIG	NULL
 #endif