[PATCH] include/uapi: Fix invalid use of BITS_PER_LONG in __swab

[Torsten Hilbrich]

This caused compile problems in user-space application using that
header. Seen with systemd:

In file included from /build/client/devel/kernel/_/usr/include/linux/byteorder/little_endian.h:13,
                 from /build/client/devel/kernel/_/usr/include/asm/byteorder.h: ,
                 from /build/client/devel/kernel/_/usr/include/linux/icmpv6.h:6,
                 from ../src/network/networkd-route.c:3:
/build/client/devel/kernel/_/usr/include/linux/swab.h: In function â__swabâ:
/build/client/devel/kernel/_/usr/include/linux/swab.h:138:5: error: "BITS_PER_LONG" is not defined, evaluates to 0 [-Werror=undef]
 #if BITS_PER_LONG == 64
     ^~~~~~~~~~~~~
cc1: some warnings being treated as errors
[181/1207] Generating sys with a custom command.
ninja: build stopped: subcommand failed.

Signed-off-by: Torsten Hilbrich <torsten.hilbrich@xxxxxxxxxxx>
---
 include/uapi/linux/swab.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h
index fa7f97da5b76..7272f85d6d6a 100644
--- a/include/uapi/linux/swab.h
+++ b/include/uapi/linux/swab.h
@@ -135,9 +135,9 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
 
 static __always_inline unsigned long __swab(const unsigned long y)
 {
-#if BITS_PER_LONG == 64
+#if __BITS_PER_LONG == 64
 	return __swab64(y);
-#else /* BITS_PER_LONG == 32 */
+#else /* __BITS_PER_LONG == 32 */
 	return __swab32(y);
 #endif
 }
-- 
2.20.1