[PATCH v3 1/2] arm64: ssbd: explicitly depend on <linux/prctl.h>

[Anisse Astier <aastier@freebox.fr>]

Fix ssbd.c which depends implicitly on asm/ptrace.h including
linux/prctl.h (through for example linux/compat.h, then linux/time.h,
linux/seqlock.h, linux/spinlock.h and linux/irqflags.h), and uses
PR_SPEC* defines.

This is an issue since we'll remove the include in the next commit.

Fixes: 9cdc0108baa8 ("arm64: ssbd: Add prctl interface for per-thread mitigation")
Cc: stable@vger.kernel.org
Signed-off-by: Anisse Astier <aastier@freebox.fr>
---
Contrary to what I said in the previous email, I can reproduce the build
error on Linus' master when ARM64_SSBD is enabled.

Changes since v2:
 - fix build when ARM64_SSBD is enabled with additionnal patch
Changes since v1:
 - made a bit more explicit that we copied defined symbols, in commit
   and code.
 - Use Fixes: tag in commit message

Thanks to Dave Martin and Will Deacon for the review, and Sasha Levin
for the auto-build bot.
---
 arch/arm64/kernel/ssbd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kernel/ssbd.c b/arch/arm64/kernel/ssbd.c
index 885f13e58708..52cfc6148355 100644
--- a/arch/arm64/kernel/ssbd.c
+++ b/arch/arm64/kernel/ssbd.c
@@ -5,6 +5,7 @@
 
 #include <linux/compat.h>
 #include <linux/errno.h>
+#include <linux/prctl.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
 #include <linux/thread_info.h>
-- 
2.19.1