proc: skip proc-empty-vm on anything but amd64 and i386

This test is arch specific, requires "munmap everything" primitive.

Link: https://lkml.kernel.org/r/20230630183434.17434-2-adobriyan@gmail.comSigned-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/proc/proc-empty-vm.c

+#if defined __amd64__ || defined __i386__
 /*
  * Copyright (c) 2022 Alexey Dobriyan <adobriyan@gmail.com>
  *
@@ -402,3 +403,9 @@ int main(void)
 
 	return rv;
 }
+#else
+int main(void)
+{
+	return 4;
+}
+#endif