__ashiftrt_r4_xx might be used from kernel module.
We need DECLARE_EXPORT() for them, otherwise we will get compile error.
This patch adds missing DECLARE_EXPORT()

ERROR: "__ashiftrt_r4_25" [drivers/iio/pressure/bmp280.ko] undefined!
ERROR: "__ashiftrt_r4_26" [drivers/iio/dac/ad5764.ko] undefined!
ERROR: "__ashiftrt_r4_26" [drivers/iio/accel/mma7660.ko] undefined!
ERROR: "__ashiftrt_r4_25" [drivers/iio/accel/dmard06.ko] undefined!
ERROR: "__ashiftrt_r4_26" [drivers/iio/accel/bma220_spi.ko] undefined!
ERROR: "__ashiftrt_r4_25" [drivers/crypto/hisilicon/sec/hisi_sec.ko] undefined!
ERROR: "__ashiftrt_r4_26" [drivers/rtc/rtc-x1205.ko] undefined!
ERROR: "__ashiftrt_r4_25" [drivers/rtc/rtc-pcf85063.ko] undefined!
ERROR: "__ashiftrt_r4_25" [drivers/rtc/rtc-pcf2123.ko] undefined!
ERROR: "__ashiftrt_r4_25" [drivers/input/tablet/gtco.ko] undefined!
ERROR: "__ashiftrt_r4_26" [drivers/input/mouse/psmouse.ko] undefined!
ERROR: "__ashiftrt_r4_28" [drivers/input/mouse/psmouse.ko] undefined!
ERROR: "__ashiftrt_r4_28" [drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.ko] undefined!
ERROR: "__ashiftrt_r4_28" [fs/udf/udf.ko] undefined!
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Rich Felker <dalias@libc.org>