asm-generic: unistd.h: fixup broken macro include.

The broken macros make the glibc compile error. If there is no
__NR3264_fstat*, we should also removed related definitions.

Reported-by: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Fixes: bf4b6a7d371e ("y2038: Remove stat64 family from default syscall set")
[arnd: Both Marcin and Guo provided this patch to fix up my clearly
       broken commit, I applied the version with the better changelog.]
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Signed-off-by: Mao Han <han_mao@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/uapi/asm-generic/unistd.h

@@ -760,8 +760,10 @@ __SYSCALL(__NR_rseq, sys_rseq)
 #define __NR_ftruncate __NR3264_ftruncate
 #define __NR_lseek __NR3264_lseek
 #define __NR_sendfile __NR3264_sendfile
+#if defined(__ARCH_WANT_NEW_STAT) || defined(__ARCH_WANT_STAT64)
 #define __NR_newfstatat __NR3264_fstatat
 #define __NR_fstat __NR3264_fstat
+#endif
 #define __NR_mmap __NR3264_mmap
 #define __NR_fadvise64 __NR3264_fadvise64
 #ifdef __NR3264_stat
@@ -776,8 +778,10 @@ __SYSCALL(__NR_rseq, sys_rseq)
 #define __NR_ftruncate64 __NR3264_ftruncate
 #define __NR_llseek __NR3264_lseek
 #define __NR_sendfile64 __NR3264_sendfile
+#if defined(__ARCH_WANT_NEW_STAT) || defined(__ARCH_WANT_STAT64)
 #define __NR_fstatat64 __NR3264_fstatat
 #define __NR_fstat64 __NR3264_fstat
+#endif
 #define __NR_mmap2 __NR3264_mmap
 #define __NR_fadvise64_64 __NR3264_fadvise64
 #ifdef __NR3264_stat