tools/nolibc: remove dead __ARCH_WANT_SYS_OLD_SELECT

The macro lost its last user when select() was reimplemented on top of
pselect6 for every architecture; sys/select.h no longer looks at it,
and nothing else in the tree does either. See commit 668e437372
("tools/nolibc/select: drop non-pselect based implementations").

The comment that goes with it is stale for the same reason, as neither
architecture can end up calling old_select any more.

Drop both from arch-x86.h and arch-arm.h.

Cc: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>
Signed-off-by: Ammar Faizi <ammarfaizi2@openresty.com>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

tools/include/nolibc/arch-arm.h

@@ -33,10 +33,7 @@
  *     with r7 before calling svc, and r6 is marked as clobbered.
  *     We're just using any regular register which we assign to r7 after saving
  *     it.
- *
- * Also, ARM supports the old_select syscall if newselect is not available
  */
-#define __ARCH_WANT_SYS_OLD_SELECT
 
 #if (defined(__THUMBEB__) || defined(__THUMBEL__)) && \
     !defined(NOLIBC_OMIT_FRAME_POINTER)

tools/include/nolibc/arch-x86.h

@@ -25,10 +25,7 @@
  *     don't have to experience issues with register constraints.
  *   - the syscall number is always specified last in order to allow to force
  *     some registers before (gcc refuses a %-register at the last position).
- *
- * Also, i386 supports the old_select syscall if newselect is not available
  */
-#define __ARCH_WANT_SYS_OLD_SELECT
 
 #define __nolibc_syscall0(num)                                                \
 ({                                                                            \