asm-generic: Make time32 syscall numbers optional

We don't want new architectures to even provide the old 32-bit time_t
based system calls any more, or define the syscall number macros.

Add a new __ARCH_WANT_TIME32_SYSCALLS macro that gets enabled for all
existing 32-bit architectures using the generic system call table,
so we don't change any current behavior.
Since this symbol is evaluated in user space as well, we cannot use
a Kconfig CONFIG_* macro but have to define it in uapi/asm/unistd.h.

On 64-bit architectures, the same system call numbers mostly refer to
the system calls we want to keep, as they already pass 64-bit time_t.

As new architectures no longer provide these, we need new exceptions
in checksyscalls.sh.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

scripts/checksyscalls.sh

@@ -143,6 +143,13 @@ cat << EOF
 #define __IGNORE_rt_sigtimedwait
 #define __IGNORE_futex
 #define __IGNORE_sched_rr_get_interval
+#define __IGNORE_gettimeofday
+#define __IGNORE_settimeofday
+#define __IGNORE_wait4
+#define __IGNORE_adjtimex
+#define __IGNORE_nanosleep
+#define __IGNORE_io_getevents
+#define __IGNORE_recvmmsg
 #endif
 
 /* i386-specific or historical system calls */