[tip:core/urgent] uapi/linux/stddef.h: Provide __always_inline to userspace headers

[tip-bot for Denys Vlasenko]

Commit-ID:  283d757378371e8044d873e661b1dccee46c5887
Gitweb:     http://git.kernel.org/tip/283d757378371e8044d873e661b1dccee46c5887
Author:     Denys Vlasenko <dvlasenk@xxxxxxxxxx>
AuthorDate: Wed, 30 Mar 2016 00:14:57 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 30 Mar 2016 12:50:17 +0200

uapi/linux/stddef.h: Provide __always_inline to userspace headers

Josh Boyer reported that my recent change to uapi/linux/swab.h broke the Qemu build:

  bc27fb68aaad ("include/uapi/linux/byteorder, swab: force inlining of some byteswap operations")

Unfortunately, UAPI headers don't include compiler.h so fixing it there is not enough,
add an __always_inline definition to uapi/linux/stddef.h instead.

Testcase: "make headers_install" and try to compile this:

	#include <linux/swab.h>
	void main() {}

Reported-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Thomas Graf <tgraf@xxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1459289697-12875-1-git-send-email-dvlasenk@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 include/uapi/linux/stddef.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h
index aa9f104..621fa8a 100644
--- a/include/uapi/linux/stddef.h
+++ b/include/uapi/linux/stddef.h
@@ -1 +1,5 @@
 #include <linux/compiler.h>
+
+#ifndef __always_inline
+#define __always_inline inline
+#endif